diff --git a/sprout/iterator/amplitude_spectrum_iterator.hpp b/sprout/iterator/amplitude_spectrum_iterator.hpp
new file mode 100644
index 00000000..58af95c0
--- /dev/null
+++ b/sprout/iterator/amplitude_spectrum_iterator.hpp
@@ -0,0 +1,37 @@
+#ifndef SPROUT_ITERATOR_AMPLITUDE_SPECTRUM_ITERATOR_HPP
+#define SPROUT_ITERATOR_AMPLITUDE_SPECTRUM_ITERATOR_HPP
+
+#include <iterator>
+#include <sprout/config.hpp>
+#include <sprout/iterator/transform_iterator.hpp>
+#include <sprout/numeric/dft/amplitude_spectrum_value.hpp>
+
+namespace sprout {
+	//
+	// amplitude_value
+	//
+	template<typename T>
+	class amplitude_value {
+	public:
+		typedef typename T::value_type result_type;
+		typedef T argument_type;
+	public:
+		SPROUT_CONSTEXPR amplitude_value() {}
+		SPROUT_CONSTEXPR typename T::value_type operator()(T const& value) const {
+			return sprout::amplitude_spectrum_value(value);
+		}
+	};
+
+	//
+	// make_amplitude_spectrum_iterator
+	//
+	template<typename Iterator>
+	inline SPROUT_CONSTEXPR sprout::transform_iterator<sprout::amplitude_value<typename std::iterator_traits<Iterator>::value_type>, Iterator>
+	make_amplitude_spectrum_iterator(Iterator it) {
+		return sprout::transform_iterator<sprout::amplitude_value<typename std::iterator_traits<Iterator>::value_type>, Iterator>(
+			it, sprout::amplitude_value<typename std::iterator_traits<Iterator>::value_type>()
+			);
+	}
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_ITERATOR_AMPLITUDE_SPECTRUM_ITERATOR_HPP
diff --git a/sprout/iterator/dft.hpp b/sprout/iterator/dft.hpp
index 2ca894a5..c58bcbca 100644
--- a/sprout/iterator/dft.hpp
+++ b/sprout/iterator/dft.hpp
@@ -4,5 +4,7 @@
 #include <sprout/config.hpp>
 #include <sprout/iterator/dft_iterator.hpp>
 #include <sprout/iterator/idft_iterator.hpp>
+#include <sprout/iterator/amplitude_spectrum_iterator.hpp>
+#include <sprout/iterator/phase_spectrum_iterator.hpp>
 
 #endif	// #ifndef SPROUT_ITERATOR_DFT_HPP
diff --git a/sprout/iterator/phase_spectrum_iterator.hpp b/sprout/iterator/phase_spectrum_iterator.hpp
new file mode 100644
index 00000000..189bf5da
--- /dev/null
+++ b/sprout/iterator/phase_spectrum_iterator.hpp
@@ -0,0 +1,37 @@
+#ifndef SPROUT_ITERATOR_PHASE_SPECTRUM_ITERATOR_HPP
+#define SPROUT_ITERATOR_PHASE_SPECTRUM_ITERATOR_HPP
+
+#include <iterator>
+#include <sprout/config.hpp>
+#include <sprout/iterator/transform_iterator.hpp>
+#include <sprout/numeric/dft/phase_spectrum_value.hpp>
+
+namespace sprout {
+	//
+	// phase_value
+	//
+	template<typename T>
+	class phase_value {
+	public:
+		typedef typename T::value_type result_type;
+		typedef T argument_type;
+	public:
+		SPROUT_CONSTEXPR phase_value() {}
+		SPROUT_CONSTEXPR typename T::value_type operator()(T const& value) const {
+			return sprout::phase_spectrum_value(value);
+		}
+	};
+
+	//
+	// make_phase_spectrum_iterator
+	//
+	template<typename Iterator>
+	inline SPROUT_CONSTEXPR sprout::transform_iterator<sprout::phase_value<typename std::iterator_traits<Iterator>::value_type>, Iterator>
+	make_phase_spectrum_iterator(Iterator it) {
+		return sprout::transform_iterator<sprout::phase_value<typename std::iterator_traits<Iterator>::value_type>, Iterator>(
+			it, sprout::phase_value<typename std::iterator_traits<Iterator>::value_type>()
+			);
+	}
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_ITERATOR_PHASE_SPECTRUM_ITERATOR_HPP
diff --git a/sprout/iterator/replace_if_iterator.hpp b/sprout/iterator/replace_if_iterator.hpp
index 50fb658b..a1cc3a72 100644
--- a/sprout/iterator/replace_if_iterator.hpp
+++ b/sprout/iterator/replace_if_iterator.hpp
@@ -1,5 +1,5 @@
-#ifndef SPROUT_ITERATOR_REPLACE_ITERATOR_HPP
-#define SPROUT_ITERATOR_REPLACE_ITERATOR_HPP
+#ifndef SPROUT_ITERATOR_REPLACE_IF_ITERATOR_HPP
+#define SPROUT_ITERATOR_REPLACE_IF_ITERATOR_HPP
 
 #include <sprout/config.hpp>
 #include <sprout/iterator/transform_iterator.hpp>
@@ -13,7 +13,7 @@ namespace sprout {
 	public:
 		typedef Predicate predicate_type;
 		typedef T result_type;
-		typedef T const& argument_type;
+		typedef T argument_type;
 	private:
 		Predicate pred_;
 		T new_;
@@ -39,4 +39,4 @@ namespace sprout {
 	}
 }	// namespace sprout
 
-#endif	// #ifndef SPROUT_ITERATOR_REPLACE_ITERATOR_HPP
+#endif	// #ifndef SPROUT_ITERATOR_REPLACE_IF_ITERATOR_HPP
diff --git a/sprout/iterator/replace_iterator.hpp b/sprout/iterator/replace_iterator.hpp
index 01c46bad..927012ee 100644
--- a/sprout/iterator/replace_iterator.hpp
+++ b/sprout/iterator/replace_iterator.hpp
@@ -1,5 +1,5 @@
-#ifndef SPROUT_ITERATOR_REPLACE_IF_ITERATOR_HPP
-#define SPROUT_ITERATOR_REPLACE_IF_ITERATOR_HPP
+#ifndef SPROUT_ITERATOR_REPLACE_ITERATOR_HPP
+#define SPROUT_ITERATOR_REPLACE_ITERATOR_HPP
 
 #include <sprout/config.hpp>
 #include <sprout/iterator/transform_iterator.hpp>
@@ -38,4 +38,4 @@ namespace sprout {
 	}
 }	// namespace sprout
 
-#endif	// #ifndef SPROUT_ITERATOR_REPLACE_IF_ITERATOR_HPP
+#endif	// #ifndef SPROUT_ITERATOR_REPLACE_ITERATOR_HPP
diff --git a/sprout/numeric/dft.hpp b/sprout/numeric/dft.hpp
index 056fcfa0..f3ca3200 100644
--- a/sprout/numeric/dft.hpp
+++ b/sprout/numeric/dft.hpp
@@ -2,13 +2,7 @@
 #define SPROUT_NUMERIC_DFT_HPP
 
 #include <sprout/config.hpp>
-#include <sprout/numeric/dft/dft.hpp>
-#include <sprout/numeric/dft/idft.hpp>
-#include <sprout/numeric/dft/dft_element.hpp>
-#include <sprout/numeric/dft/idft_element.hpp>
-#include <sprout/numeric/dft/spectrum.hpp>
-#include <sprout/numeric/dft/amplitude_spectrum_value.hpp>
-#include <sprout/numeric/dft/phase_spectrum_value.hpp>
-#include <sprout/numeric/dft/wave.hpp>
+#include <sprout/numeric/dft/non_modifying.hpp>
+#include <sprout/numeric/dft/modifying.hpp>
 
 #endif	// #ifndef SPROUT_NUMERIC_DFT_HPP
diff --git a/sprout/numeric/dft/dft_element.hpp b/sprout/numeric/dft/dft_element.hpp
index 223d8fe7..702182e2 100644
--- a/sprout/numeric/dft/dft_element.hpp
+++ b/sprout/numeric/dft/dft_element.hpp
@@ -3,9 +3,9 @@
 
 #include <iterator>
 #include <sprout/config.hpp>
-#include <sprout/numeric/dft/detail/dft_element_gen.hpp>
 #include <sprout/math/constants.hpp>
 #include <sprout/iterator/operation.hpp>
+#include <sprout/numeric/dft/detail/dft_element_gen.hpp>
 
 namespace sprout {
 	namespace detail {
diff --git a/sprout/numeric/dft/fit.hpp b/sprout/numeric/dft/fit.hpp
new file mode 100644
index 00000000..d58c4dfb
--- /dev/null
+++ b/sprout/numeric/dft/fit.hpp
@@ -0,0 +1,10 @@
+#ifndef SPROUT_NUMERIC_DFT_FIT_HPP
+#define SPROUT_NUMERIC_DFT_FIT_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/numeric/dft/fit/dft.hpp>
+#include <sprout/numeric/dft/fit/idft.hpp>
+#include <sprout/numeric/dft/fit/spectrum.hpp>
+#include <sprout/numeric/dft/fit/wave.hpp>
+
+#endif	// #ifndef SPROUT_NUMERIC_DFT_FIT_HPP
diff --git a/sprout/numeric/dft/fit/amplitude_spectrum.hpp b/sprout/numeric/dft/fit/amplitude_spectrum.hpp
index d878e7e3..494cb63e 100644
--- a/sprout/numeric/dft/fit/amplitude_spectrum.hpp
+++ b/sprout/numeric/dft/fit/amplitude_spectrum.hpp
@@ -2,13 +2,15 @@
 #define SPROUT_NUMERIC_DFT_FIT_AMPLITUDE_SPECTRUM_HPP
 
 #include <sprout/config.hpp>
+#include <sprout/iterator/distance.hpp>
 #include <sprout/container/traits.hpp>
 #include <sprout/container/functions.hpp>
 #include <sprout/numeric/dft/fixed/amplitude_spectrum.hpp>
 #include <sprout/algorithm/fit/result_of.hpp>
 #include <sprout/sub_array.hpp>
-#include <sprout/iterator/operation.hpp>
+#include <sprout/pit.hpp>
 #include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
+#include <sprout/iterator/type_traits/is_iterator.hpp>
 
 namespace sprout {
 	namespace fit {
@@ -33,8 +35,15 @@ namespace sprout {
 		template<typename InputIterator, typename Result>
 		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
 		amplitude_spectrum(InputIterator first, InputIterator last, Result const& result) {
+			static_assert(sprout::is_forward_iterator<InputIterator>::value, "Sorry, not implemented.");
 			return sprout::fit::detail::amplitude_spectrum_impl(first, last, result, sprout::internal_begin_offset(result));
 		}
+
+		template<typename Result, typename InputIterator>
+		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
+		amplitude_spectrum(InputIterator first, InputIterator last) {
+			return sprout::fit::amplitude_spectrum(first, last, sprout::pit<Result>());
+		}
 	}	// namespace fit
 }	// namespace sprout
 
diff --git a/sprout/numeric/dft/fit/dft.hpp b/sprout/numeric/dft/fit/dft.hpp
index e7174207..318d43a7 100644
--- a/sprout/numeric/dft/fit/dft.hpp
+++ b/sprout/numeric/dft/fit/dft.hpp
@@ -2,21 +2,22 @@
 #define SPROUT_NUMERIC_DFT_FIT_DFT_HPP
 
 #include <sprout/config.hpp>
+#include <sprout/iterator/distance.hpp>
 #include <sprout/container/traits.hpp>
 #include <sprout/container/functions.hpp>
 #include <sprout/numeric/dft/fixed/dft.hpp>
 #include <sprout/algorithm/fit/result_of.hpp>
 #include <sprout/sub_array.hpp>
-#include <sprout/iterator/operation.hpp>
+#include <sprout/pit.hpp>
 #include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
 
 namespace sprout {
 	namespace fit {
 		namespace detail {
-			template<typename InputIterator, typename Result>
+			template<typename ForwardIterator, typename Result>
 			inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
 			dft_impl(
-				InputIterator first, InputIterator last, Result const& result,
+				ForwardIterator first, ForwardIterator last, Result const& result,
 				typename sprout::container_traits<Result>::difference_type offset
 				)
 			{
@@ -30,11 +31,17 @@ namespace sprout {
 		//
 		// dft
 		//
-		template<typename InputIterator, typename Result>
+		template<typename ForwardIterator, typename Result>
 		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
-		dft(InputIterator first, InputIterator last, Result const& result) {
+		dft(ForwardIterator first, ForwardIterator last, Result const& result) {
 			return sprout::fit::detail::dft_impl(first, last, result, sprout::internal_begin_offset(result));
 		}
+
+		template<typename Result, typename ForwardIterator>
+		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+		dft(ForwardIterator first, ForwardIterator last) {
+			return sprout::fit::dft(first, last, sprout::pit<Result>());
+		}
 	}	// namespace fit
 }	// namespace sprout
 
diff --git a/sprout/numeric/dft/fit/idft.hpp b/sprout/numeric/dft/fit/idft.hpp
index 70ef18e9..8ad9a61c 100644
--- a/sprout/numeric/dft/fit/idft.hpp
+++ b/sprout/numeric/dft/fit/idft.hpp
@@ -2,21 +2,22 @@
 #define SPROUT_NUMERIC_DFT_FIT_IDFT_HPP
 
 #include <sprout/config.hpp>
+#include <sprout/iterator/distance.hpp>
 #include <sprout/container/traits.hpp>
 #include <sprout/container/functions.hpp>
 #include <sprout/numeric/dft/fixed/idft.hpp>
 #include <sprout/algorithm/fit/result_of.hpp>
 #include <sprout/sub_array.hpp>
-#include <sprout/iterator/operation.hpp>
+#include <sprout/pit.hpp>
 #include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
 
 namespace sprout {
 	namespace fit {
 		namespace detail {
-			template<typename InputIterator, typename Result>
+			template<typename ForwardIterator, typename Result>
 			inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
 			idft_impl(
-				InputIterator first, InputIterator last, Result const& result,
+				ForwardIterator first, ForwardIterator last, Result const& result,
 				typename sprout::container_traits<Result>::difference_type offset
 				)
 			{
@@ -30,11 +31,17 @@ namespace sprout {
 		//
 		// idft
 		//
-		template<typename InputIterator, typename Result>
+		template<typename ForwardIterator, typename Result>
 		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
-		idft(InputIterator first, InputIterator last, Result const& result) {
+		idft(ForwardIterator first, ForwardIterator last, Result const& result) {
 			return sprout::fit::detail::idft_impl(first, last, result, sprout::internal_begin_offset(result));
 		}
+
+		template<typename Result, typename ForwardIterator>
+		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+		idft(ForwardIterator first, ForwardIterator last) {
+			return sprout::fit::idft(first, last, sprout::pit<Result>());
+		}
 	}	// namespace fit
 }	// namespace sprout
 
diff --git a/sprout/numeric/dft/fit/phase_spectrum.hpp b/sprout/numeric/dft/fit/phase_spectrum.hpp
index 15dc20f6..e883fc55 100644
--- a/sprout/numeric/dft/fit/phase_spectrum.hpp
+++ b/sprout/numeric/dft/fit/phase_spectrum.hpp
@@ -2,13 +2,15 @@
 #define SPROUT_NUMERIC_DFT_FIT_PHASE_SPECTRUM_HPP
 
 #include <sprout/config.hpp>
+#include <sprout/iterator/distance.hpp>
 #include <sprout/container/traits.hpp>
 #include <sprout/container/functions.hpp>
 #include <sprout/numeric/dft/fixed/phase_spectrum.hpp>
 #include <sprout/algorithm/fit/result_of.hpp>
 #include <sprout/sub_array.hpp>
-#include <sprout/iterator/operation.hpp>
+#include <sprout/pit.hpp>
 #include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
+#include <sprout/iterator/type_traits/is_iterator.hpp>
 
 namespace sprout {
 	namespace fit {
@@ -33,8 +35,15 @@ namespace sprout {
 		template<typename InputIterator, typename Result>
 		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
 		phase_spectrum(InputIterator first, InputIterator last, Result const& result) {
+			static_assert(sprout::is_forward_iterator<InputIterator>::value, "Sorry, not implemented.");
 			return sprout::fit::detail::phase_spectrum_impl(first, last, result, sprout::internal_begin_offset(result));
 		}
+
+		template<typename Result, typename InputIterator>
+		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
+		phase_spectrum(InputIterator first, InputIterator last) {
+			return sprout::fit::phase_spectrum(first, last, sprout::pit<Result>());
+		}
 	}	// namespace fit
 }	// namespace sprout
 
diff --git a/sprout/numeric/dft/fit/sawtooth.hpp b/sprout/numeric/dft/fit/sawtooth.hpp
index 3d146529..c22bb99d 100644
--- a/sprout/numeric/dft/fit/sawtooth.hpp
+++ b/sprout/numeric/dft/fit/sawtooth.hpp
@@ -7,6 +7,7 @@
 #include <sprout/numeric/dft/fixed/sawtooth.hpp>
 #include <sprout/algorithm/fit/result_of.hpp>
 #include <sprout/sub_array.hpp>
+#include <sprout/pit.hpp>
 
 namespace sprout {
 	namespace fit {
@@ -40,7 +41,18 @@ namespace sprout {
 			typename sprout::container_traits<Container>::value_type const& phase = 0
 			)
 		{
-			return sprout::fit::detail::sawtooth_impl(cont, frequency, amplitude, sprout::internal_begin_offset(cont));
+			return sprout::fit::detail::sawtooth_impl(cont, frequency, amplitude, phase, sprout::internal_begin_offset(cont));
+		}
+
+		template<typename Container>
+		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Container>::type
+		sawtooth(
+			typename sprout::container_traits<Container>::value_type const& frequency = 1,
+			typename sprout::container_traits<Container>::value_type const& amplitude = 1,
+			typename sprout::container_traits<Container>::value_type const& phase = 0
+			)
+		{
+			return sprout::fit::sawtooth(sprout::pit<Container>(), frequency, amplitude, phase);
 		}
 	}	// namespace fit
 }	// namespace sprout
diff --git a/sprout/numeric/dft/fit/sinusoid.hpp b/sprout/numeric/dft/fit/sinusoid.hpp
index 5070ff36..19c5eb26 100644
--- a/sprout/numeric/dft/fit/sinusoid.hpp
+++ b/sprout/numeric/dft/fit/sinusoid.hpp
@@ -7,6 +7,7 @@
 #include <sprout/numeric/dft/fixed/sinusoid.hpp>
 #include <sprout/algorithm/fit/result_of.hpp>
 #include <sprout/sub_array.hpp>
+#include <sprout/pit.hpp>
 
 namespace sprout {
 	namespace fit {
@@ -40,7 +41,18 @@ namespace sprout {
 			typename sprout::container_traits<Container>::value_type const& phase = 0
 			)
 		{
-			return sprout::fit::detail::sinusoid_impl(cont, frequency, amplitude, sprout::internal_begin_offset(cont));
+			return sprout::fit::detail::sinusoid_impl(cont, frequency, amplitude, phase, sprout::internal_begin_offset(cont));
+		}
+
+		template<typename Container>
+		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Container>::type
+		sinusoid(
+			typename sprout::container_traits<Container>::value_type const& frequency = 1,
+			typename sprout::container_traits<Container>::value_type const& amplitude = 1,
+			typename sprout::container_traits<Container>::value_type const& phase = 0
+			)
+		{
+			return sprout::fit::sinusoid(sprout::pit<Container>(), frequency, amplitude, phase);
 		}
 	}	// namespace fit
 }	// namespace sprout
diff --git a/sprout/numeric/dft/fit/spectrum.hpp b/sprout/numeric/dft/fit/spectrum.hpp
index 88f3715a..4409a14b 100644
--- a/sprout/numeric/dft/fit/spectrum.hpp
+++ b/sprout/numeric/dft/fit/spectrum.hpp
@@ -15,6 +15,12 @@ namespace sprout {
 		spectrum(InputIterator first, InputIterator last, Result const& result) {
 			return sprout::fit::amplitude_spectrum(first, last, result);
 		}
+
+		template<typename Result, typename InputIterator>
+		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
+		spectrum(InputIterator first, InputIterator last) {
+			return sprout::fit::amplitude_spectrum<Result>(first, last);
+		}
 	}	// namespace fit
 }	// namespace sprout
 
diff --git a/sprout/numeric/dft/fit/square.hpp b/sprout/numeric/dft/fit/square.hpp
index ec9b6499..a18da0b4 100644
--- a/sprout/numeric/dft/fit/square.hpp
+++ b/sprout/numeric/dft/fit/square.hpp
@@ -7,6 +7,7 @@
 #include <sprout/numeric/dft/fixed/square.hpp>
 #include <sprout/algorithm/fit/result_of.hpp>
 #include <sprout/sub_array.hpp>
+#include <sprout/pit.hpp>
 
 namespace sprout {
 	namespace fit {
@@ -42,7 +43,19 @@ namespace sprout {
 			typename sprout::container_traits<Container>::value_type const& duty = 0.5
 			)
 		{
-			return sprout::fit::detail::square_impl(cont, frequency, amplitude, duty, sprout::internal_begin_offset(cont));
+			return sprout::fit::detail::square_impl(cont, frequency, amplitude, phase, duty, sprout::internal_begin_offset(cont));
+		}
+
+		template<typename Container>
+		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Container>::type
+		square(
+			typename sprout::container_traits<Container>::value_type const& frequency = 1,
+			typename sprout::container_traits<Container>::value_type const& amplitude = 1,
+			typename sprout::container_traits<Container>::value_type const& phase = 0,
+			typename sprout::container_traits<Container>::value_type const& duty = 0.5
+			)
+		{
+			return sprout::fit::square(sprout::pit<Container>(), frequency, amplitude, phase, duty);
 		}
 	}	// namespace fit
 }	// namespace sprout
diff --git a/sprout/numeric/dft/fit/triangle.hpp b/sprout/numeric/dft/fit/triangle.hpp
index 39228ddf..e9e3c863 100644
--- a/sprout/numeric/dft/fit/triangle.hpp
+++ b/sprout/numeric/dft/fit/triangle.hpp
@@ -7,6 +7,7 @@
 #include <sprout/numeric/dft/fixed/triangle.hpp>
 #include <sprout/algorithm/fit/result_of.hpp>
 #include <sprout/sub_array.hpp>
+#include <sprout/pit.hpp>
 
 namespace sprout {
 	namespace fit {
@@ -40,7 +41,18 @@ namespace sprout {
 			typename sprout::container_traits<Container>::value_type const& phase = 0
 			)
 		{
-			return sprout::fit::detail::triangle_impl(cont, frequency, amplitude, sprout::internal_begin_offset(cont));
+			return sprout::fit::detail::triangle_impl(cont, frequency, amplitude, phase, sprout::internal_begin_offset(cont));
+		}
+
+		template<typename Container>
+		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Container>::type
+		triangle(
+			typename sprout::container_traits<Container>::value_type const& frequency = 1,
+			typename sprout::container_traits<Container>::value_type const& amplitude = 1,
+			typename sprout::container_traits<Container>::value_type const& phase = 0
+			)
+		{
+			return sprout::fit::triangle(sprout::pit<Container>(), frequency, amplitude, phase);
 		}
 	}	// namespace fit
 }	// namespace sprout
diff --git a/sprout/numeric/dft/fixed.hpp b/sprout/numeric/dft/fixed.hpp
new file mode 100644
index 00000000..ab97255c
--- /dev/null
+++ b/sprout/numeric/dft/fixed.hpp
@@ -0,0 +1,10 @@
+#ifndef SPROUT_NUMERIC_DFT_FIXED_HPP
+#define SPROUT_NUMERIC_DFT_FIXED_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/numeric/dft/fixed/dft.hpp>
+#include <sprout/numeric/dft/fixed/idft.hpp>
+#include <sprout/numeric/dft/fixed/spectrum.hpp>
+#include <sprout/numeric/dft/fixed/wave.hpp>
+
+#endif	// #ifndef SPROUT_NUMERIC_DFT_FIXED_HPP
diff --git a/sprout/numeric/dft/fixed/amplitude_spectrum.hpp b/sprout/numeric/dft/fixed/amplitude_spectrum.hpp
index 9117d3d2..9ad282dc 100644
--- a/sprout/numeric/dft/fixed/amplitude_spectrum.hpp
+++ b/sprout/numeric/dft/fixed/amplitude_spectrum.hpp
@@ -1,21 +1,27 @@
 #ifndef SPROUT_NUMERIC_DFT_FIXED_AMPLITUDE_SPECTRUM_HPP
 #define SPROUT_NUMERIC_DFT_FIXED_AMPLITUDE_SPECTRUM_HPP
 
+#include <iterator>
+#include <type_traits>
 #include <sprout/config.hpp>
 #include <sprout/index_tuple.hpp>
 #include <sprout/container/traits.hpp>
 #include <sprout/container/functions.hpp>
 #include <sprout/iterator/operation.hpp>
+#include <sprout/iterator/amplitude_spectrum_iterator.hpp>
 #include <sprout/algorithm/fixed/result_of.hpp>
+#include <sprout/pit.hpp>
+#include <sprout/math/comparison.hpp>
 #include <sprout/numeric/dft/amplitude_spectrum_value.hpp>
+#include <sprout/detail/container_complate.hpp>
 
 namespace sprout {
 	namespace fixed {
 		namespace detail {
-			template<typename InputIterator, typename Result, sprout::index_t... Indexes>
+			template<typename RandomAccessIterator, typename Result, sprout::index_t... Indexes>
 			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
-			amplitude_spectrum_impl(
-				InputIterator first, InputIterator last, Result const& result,
+			amplitude_spectrum_impl_ra(
+				RandomAccessIterator first, RandomAccessIterator last, Result const& result,
 				sprout::index_tuple<Indexes...>,
 				typename sprout::container_traits<Result>::difference_type offset,
 				typename sprout::container_traits<Result>::size_type size,
@@ -23,27 +29,93 @@ namespace sprout {
 				)
 			{
 				return sprout::remake<Result>(
-					result,
-					size,
-					(Indexes >= offset && Indexes < offset + size && Indexes < offset + input_size
-						? sprout::amplitude_spectrum_value(*sprout::next(first, Indexes))
+					result, size,
+					(Indexes >= offset && sprout::math::less(Indexes, offset + size) && sprout::math::less(Indexes, offset + input_size)
+						? sprout::amplitude_spectrum_value(first[Indexes])
 						: *sprout::next(sprout::internal_begin(result), Indexes)
 						)...
 					);
 			}
-			template<typename InputIterator, typename Result>
+			template<typename RandomAccessIterator, typename Result>
 			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
-			amplitude_spectrum(InputIterator first, InputIterator last, Result const& result) {
-				return sprout::fixed::detail::amplitude_spectrum_impl(
-					first,
-					last,
-					result,
+			amplitude_spectrum(
+				RandomAccessIterator first, RandomAccessIterator last, Result const& result,
+				std::random_access_iterator_tag*
+				)
+			{
+				return sprout::fixed::detail::amplitude_spectrum_impl_ra(
+					first, last, result,
 					sprout::index_range<0, sprout::container_traits<Result>::static_size>::make(),
 					sprout::internal_begin_offset(result),
 					sprout::size(result),
 					sprout::distance(first, last)
 					);
 			}
+
+			template<typename ForwardIterator, typename Result, typename... Args>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				sprout::container_traits<Result>::static_size == sizeof...(Args),
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			amplitude_spectrum_impl(
+				ForwardIterator first, ForwardIterator last, Result const& result,
+				typename sprout::container_traits<Result>::size_type size,
+				Args const&... args
+				)
+			{
+				return sprout::remake<Result>(result, sprout::size(result), args...);
+			}
+			template<typename ForwardIterator, typename Result, typename... Args>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				sprout::container_traits<Result>::static_size != sizeof...(Args),
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			amplitude_spectrum_impl(
+				ForwardIterator first, ForwardIterator last, Result const& result,
+				typename sprout::container_traits<Result>::size_type size,
+				Args const&... args
+				)
+			{
+				return first != last && sizeof...(Args) < size
+					? sprout::fixed::detail::amplitude_spectrum_impl(
+						sprout::next(first), last, result, size,
+						args..., sprout::amplitude_spectrum_value(*first)
+						)
+					: sprout::detail::container_complate(result, args...)
+					;
+			}
+			template<typename ForwardIterator, typename Result>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			amplitude_spectrum(
+				ForwardIterator first, ForwardIterator last, Result const& result,
+				void*
+				)
+			{
+				return sprout::fixed::detail::amplitude_spectrum_impl(first, last, result, sprout::size(result));
+			}
+
+			template<typename InputIterator, typename Result>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				sprout::is_fixed_container<Result>::value,
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			amplitude_spectrum(InputIterator first, InputIterator last, Result const& result) {
+				typedef typename std::iterator_traits<InputIterator>::iterator_category* category;
+				return sprout::fixed::detail::amplitude_spectrum(first, last, result, category());
+			}
+
+			template<typename InputIterator, typename Result>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				!sprout::is_fixed_container<Result>::value,
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			amplitude_spectrum(InputIterator first, InputIterator last, Result const& result) {
+				return sprout::remake<Result>(
+					result, sprout::size(result),
+					sprout::make_amplitude_spectrum_iterator(first),
+					sprout::make_amplitude_spectrum_iterator(last)
+					);
+			}
 		}	// namespace detail
 		//
 		// amplitude_spectrum
@@ -53,6 +125,12 @@ namespace sprout {
 		amplitude_spectrum(InputIterator first, InputIterator last, Result const& result) {
 			return sprout::fixed::detail::amplitude_spectrum(first, last, result);
 		}
+
+		template<typename Result, typename ForwardIterator>
+		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+		amplitude_spectrum(ForwardIterator first, ForwardIterator last) {
+			return sprout::fixed::amplitude_spectrum(first, last, sprout::pit<Result>());
+		}
 	}	// namespace fixed
 
 	using sprout::fixed::amplitude_spectrum;
diff --git a/sprout/numeric/dft/fixed/dft.hpp b/sprout/numeric/dft/fixed/dft.hpp
index 7b013b10..e84d10ed 100644
--- a/sprout/numeric/dft/fixed/dft.hpp
+++ b/sprout/numeric/dft/fixed/dft.hpp
@@ -1,21 +1,27 @@
 #ifndef SPROUT_NUMERIC_DFT_FIXED_DFT_HPP
 #define SPROUT_NUMERIC_DFT_FIXED_DFT_HPP
 
+#include <iterator>
+#include <type_traits>
 #include <sprout/config.hpp>
 #include <sprout/index_tuple.hpp>
 #include <sprout/container/traits.hpp>
 #include <sprout/container/functions.hpp>
 #include <sprout/iterator/operation.hpp>
+#include <sprout/iterator/dft_iterator.hpp>
 #include <sprout/algorithm/fixed/result_of.hpp>
+#include <sprout/pit.hpp>
+#include <sprout/math/comparison.hpp>
 #include <sprout/numeric/dft/dft_element.hpp>
+#include <sprout/detail/container_complate.hpp>
 
 namespace sprout {
 	namespace fixed {
 		namespace detail {
-			template<typename InputIterator, typename Result, sprout::index_t... Indexes>
+			template<typename RandomAccessIterator, typename Result, sprout::index_t... Indexes>
 			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
-			dft_impl(
-				InputIterator first, InputIterator last, Result const& result,
+			dft_impl_ra(
+				RandomAccessIterator first, RandomAccessIterator last, Result const& result,
 				sprout::index_tuple<Indexes...>,
 				typename sprout::container_traits<Result>::difference_type offset,
 				typename sprout::container_traits<Result>::size_type size,
@@ -23,36 +29,110 @@ namespace sprout {
 				)
 			{
 				return sprout::remake<Result>(
-					result,
-					size,
-					(Indexes >= offset && Indexes < offset + size && Indexes < offset + input_size
+					result, size,
+					(Indexes >= offset && sprout::math::less(Indexes, offset + size) && sprout::math::less(Indexes, offset + input_size)
 						? sprout::detail::dft_element_impl(first, last, Indexes - offset, input_size)
 						: *sprout::next(sprout::internal_begin(result), Indexes)
 						)...
 					);
 			}
-			template<typename InputIterator, typename Result>
+			template<typename RandomAccessIterator, typename Result>
 			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
-			dft(InputIterator first, InputIterator last, Result const& result) {
-				return sprout::fixed::detail::dft_impl(
-					first,
-					last,
-					result,
+			dft(
+				RandomAccessIterator first, RandomAccessIterator last, Result const& result,
+				std::random_access_iterator_tag*
+				)
+			{
+				return sprout::fixed::detail::dft_impl_ra(
+					first, last, result,
 					sprout::index_range<0, sprout::container_traits<Result>::static_size>::make(),
 					sprout::internal_begin_offset(result),
 					sprout::size(result),
 					sprout::distance(first, last)
 					);
 			}
+
+			template<typename ForwardIterator, typename Result, typename... Args>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				sprout::container_traits<Result>::static_size == sizeof...(Args),
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			dft_impl(
+				ForwardIterator first, ForwardIterator last, Result const& result,
+				typename sprout::container_traits<Result>::size_type size,
+				ForwardIterator first_, typename sprout::container_traits<Result>::difference_type i,
+				Args const&... args
+				)
+			{
+				return sprout::remake<Result>(result, sprout::size(result), args...);
+			}
+			template<typename ForwardIterator, typename Result, typename... Args>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				sprout::container_traits<Result>::static_size != sizeof...(Args),
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			dft_impl(
+				ForwardIterator first, ForwardIterator last, Result const& result,
+				typename sprout::container_traits<Result>::size_type size,
+				ForwardIterator first_, typename sprout::container_traits<Result>::difference_type i,
+				Args const&... args
+				)
+			{
+				return first != last && sizeof...(Args) < size
+					? sprout::fixed::detail::dft_impl(
+						sprout::next(first), last, result, size, first_, i + 1,
+						args..., sprout::detail::dft_element_impl(first_, last, i, size)
+						)
+					: sprout::detail::container_complate(result, args...)
+					;
+			}
+			template<typename ForwardIterator, typename Result>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			dft(
+				ForwardIterator first, ForwardIterator last, Result const& result,
+				void*
+				)
+			{
+				return sprout::fixed::detail::dft_impl(first, last, result, sprout::size(result), first, 0);
+			}
+
+			template<typename ForwardIterator, typename Result>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				sprout::is_fixed_container<Result>::value,
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			dft(ForwardIterator first, ForwardIterator last, Result const& result) {
+				typedef typename std::iterator_traits<ForwardIterator>::iterator_category* category;
+				return sprout::fixed::detail::dft(first, last, result, category());
+			}
+
+			template<typename ForwardIterator, typename Result>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				!sprout::is_fixed_container<Result>::value,
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			dft(ForwardIterator first, ForwardIterator last, Result const& result) {
+				return sprout::remake<Result>(
+					result, sprout::size(result),
+					sprout::make_dft_iterator(first, last),
+					sprout::make_dft_iterator(first, last, sprout::distance(first, last))
+					);
+			}
 		}	// namespace detail
 		//
 		// dft
 		//
-		template<typename InputIterator, typename Result>
+		template<typename ForwardIterator, typename Result>
 		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
-		dft(InputIterator first, InputIterator last, Result const& result) {
+		dft(ForwardIterator first, ForwardIterator last, Result const& result) {
 			return sprout::fixed::detail::dft(first, last, result);
 		}
+
+		template<typename Result, typename ForwardIterator>
+		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+		dft(ForwardIterator first, ForwardIterator last) {
+			return sprout::fixed::dft(first, last, sprout::pit<Result>());
+		}
 	}	// namespace fixed
 
 	using sprout::fixed::dft;
diff --git a/sprout/numeric/dft/fixed/idft.hpp b/sprout/numeric/dft/fixed/idft.hpp
index 6c7f0501..2c687886 100644
--- a/sprout/numeric/dft/fixed/idft.hpp
+++ b/sprout/numeric/dft/fixed/idft.hpp
@@ -1,21 +1,27 @@
 #ifndef SPROUT_NUMERIC_DFT_FIXED_IDFT_HPP
 #define SPROUT_NUMERIC_DFT_FIXED_IDFT_HPP
 
+#include <iterator>
+#include <type_traits>
 #include <sprout/config.hpp>
 #include <sprout/index_tuple.hpp>
 #include <sprout/container/traits.hpp>
 #include <sprout/container/functions.hpp>
 #include <sprout/iterator/operation.hpp>
+#include <sprout/iterator/idft_iterator.hpp>
 #include <sprout/algorithm/fixed/result_of.hpp>
+#include <sprout/pit.hpp>
+#include <sprout/math/comparison.hpp>
 #include <sprout/numeric/dft/idft_element.hpp>
+#include <sprout/detail/container_complate.hpp>
 
 namespace sprout {
 	namespace fixed {
 		namespace detail {
-			template<typename InputIterator, typename Result, sprout::index_t... Indexes>
+			template<typename RandomAccessIterator, typename Result, sprout::index_t... Indexes>
 			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
-			idft_impl(
-				InputIterator first, InputIterator last, Result const& result,
+			idft_impl_ra(
+				RandomAccessIterator first, RandomAccessIterator last, Result const& result,
 				sprout::index_tuple<Indexes...>,
 				typename sprout::container_traits<Result>::difference_type offset,
 				typename sprout::container_traits<Result>::size_type size,
@@ -23,36 +29,110 @@ namespace sprout {
 				)
 			{
 				return sprout::remake<Result>(
-					result,
-					size,
-					(Indexes >= offset && Indexes < offset + size && Indexes < offset + input_size
+					result, size,
+					(Indexes >= offset && sprout::math::less(Indexes, offset + size) && sprout::math::less(Indexes, offset + input_size)
 						? sprout::detail::idft_element_impl(first, last, Indexes - offset, input_size)
 						: *sprout::next(sprout::internal_begin(result), Indexes)
 						)...
 					);
 			}
-			template<typename InputIterator, typename Result>
+			template<typename RandomAccessIterator, typename Result>
 			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
-			idft(InputIterator first, InputIterator last, Result const& result) {
-				return sprout::fixed::detail::idft_impl(
-					first,
-					last,
-					result,
+			idft(
+				RandomAccessIterator first, RandomAccessIterator last, Result const& result,
+				std::random_access_iterator_tag*
+				)
+			{
+				return sprout::fixed::detail::idft_impl_ra(
+					first, last, result,
 					sprout::index_range<0, sprout::container_traits<Result>::static_size>::make(),
 					sprout::internal_begin_offset(result),
 					sprout::size(result),
 					sprout::distance(first, last)
 					);
 			}
+
+			template<typename ForwardIterator, typename Result, typename... Args>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				sprout::container_traits<Result>::static_size == sizeof...(Args),
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			idft_impl(
+				ForwardIterator first, ForwardIterator last, Result const& result,
+				typename sprout::container_traits<Result>::size_type size,
+				ForwardIterator first_, typename sprout::container_traits<Result>::difference_type i,
+				Args const&... args
+				)
+			{
+				return sprout::remake<Result>(result, sprout::size(result), args...);
+			}
+			template<typename ForwardIterator, typename Result, typename... Args>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				sprout::container_traits<Result>::static_size != sizeof...(Args),
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			idft_impl(
+				ForwardIterator first, ForwardIterator last, Result const& result,
+				typename sprout::container_traits<Result>::size_type size,
+				ForwardIterator first_, typename sprout::container_traits<Result>::difference_type i,
+				Args const&... args
+				)
+			{
+				return first != last && sizeof...(Args) < size
+					? sprout::fixed::detail::idft_impl(
+						sprout::next(first), last, result, size, first_, i + 1,
+						args..., sprout::detail::idft_element_impl(first_, last, i, size)
+						)
+					: sprout::detail::container_complate(result, args...)
+					;
+			}
+			template<typename ForwardIterator, typename Result>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			idft(
+				ForwardIterator first, ForwardIterator last, Result const& result,
+				void*
+				)
+			{
+				return sprout::fixed::detail::idft_impl(first, last, result, sprout::size(result), first, 0);
+			}
+
+			template<typename ForwardIterator, typename Result>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				sprout::is_fixed_container<Result>::value,
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			idft(ForwardIterator first, ForwardIterator last, Result const& result) {
+				typedef typename std::iterator_traits<ForwardIterator>::iterator_category* category;
+				return sprout::fixed::detail::idft(first, last, result, category());
+			}
+
+			template<typename ForwardIterator, typename Result>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				!sprout::is_fixed_container<Result>::value,
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			idft(ForwardIterator first, ForwardIterator last, Result const& result) {
+				return sprout::remake<Result>(
+					result, sprout::size(result),
+					sprout::make_idft_iterator(first, last),
+					sprout::make_idft_iterator(first, last, sprout::distance(first, last))
+					);
+			}
 		}	// namespace detail
 		//
 		// idft
 		//
-		template<typename InputIterator, typename Result>
+		template<typename ForwardIterator, typename Result>
 		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
-		idft(InputIterator first, InputIterator last, Result const& result) {
+		idft(ForwardIterator first, ForwardIterator last, Result const& result) {
 			return sprout::fixed::detail::idft(first, last, result);
 		}
+
+		template<typename Result, typename ForwardIterator>
+		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+		idft(ForwardIterator first, ForwardIterator last) {
+			return sprout::fixed::idft(first, last, sprout::pit<Result>());
+		}
 	}	// namespace fixed
 
 	using sprout::fixed::idft;
diff --git a/sprout/numeric/dft/fixed/phase_spectrum.hpp b/sprout/numeric/dft/fixed/phase_spectrum.hpp
index 08a49511..ad0fdc73 100644
--- a/sprout/numeric/dft/fixed/phase_spectrum.hpp
+++ b/sprout/numeric/dft/fixed/phase_spectrum.hpp
@@ -1,42 +1,49 @@
 #ifndef SPROUT_NUMERIC_DFT_FIXED_PHASE_SPECTRUM_HPP
 #define SPROUT_NUMERIC_DFT_FIXED_PHASE_SPECTRUM_HPP
 
+#include <iterator>
+#include <type_traits>
 #include <sprout/config.hpp>
 #include <sprout/index_tuple.hpp>
 #include <sprout/container/traits.hpp>
 #include <sprout/container/functions.hpp>
 #include <sprout/iterator/operation.hpp>
+#include <sprout/iterator/phase_spectrum_iterator.hpp>
 #include <sprout/algorithm/fixed/result_of.hpp>
+#include <sprout/pit.hpp>
+#include <sprout/math/comparison.hpp>
 #include <sprout/numeric/dft/phase_spectrum_value.hpp>
+#include <sprout/detail/container_complate.hpp>
 
 namespace sprout {
 	namespace fixed {
 		namespace detail {
-			template<typename InputIterator, typename Result, sprout::index_t... Indexes>
+			template<typename RandomAccessIterator, typename Result, sprout::index_t... Indexes>
 			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
-			phase_spectrum_impl(
-				InputIterator first, InputIterator last, Result const& result,
+			phase_spectrum_impl_ra(
+				RandomAccessIterator first, RandomAccessIterator last, Result const& result,
 				sprout::index_tuple<Indexes...>,
 				typename sprout::container_traits<Result>::difference_type offset,
 				typename sprout::container_traits<Result>::size_type size,
 				typename sprout::container_traits<Result>::size_type input_size
 				)
 			{
-				using sprout::real;
-				using sprout::imag;
 				return sprout::remake<Result>(
-					result,
-					size,
-					(Indexes >= offset && Indexes < offset + size && Indexes < offset + input_size
-						? sprout::phase_spectrum_value(*sprout::next(first, Indexes))
+					result, size,
+					(Indexes >= offset && sprout::math::less(Indexes, offset + size) && sprout::math::less(Indexes, offset + input_size)
+						? sprout::phase_spectrum_value(first[Indexes])
 						: *sprout::next(sprout::internal_begin(result), Indexes)
 						)...
 					);
 			}
-			template<typename InputIterator, typename Result>
+			template<typename RandomAccessIterator, typename Result>
 			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
-			phase_spectrum(InputIterator first, InputIterator last, Result const& result) {
-				return sprout::fixed::detail::phase_spectrum_impl(
+			phase_spectrum(
+				RandomAccessIterator first, RandomAccessIterator last, Result const& result,
+				std::random_access_iterator_tag*
+				)
+			{
+				return sprout::fixed::detail::phase_spectrum_impl_ra(
 					first, last, result,
 					sprout::index_range<0, sprout::container_traits<Result>::static_size>::make(),
 					sprout::internal_begin_offset(result),
@@ -44,6 +51,71 @@ namespace sprout {
 					sprout::distance(first, last)
 					);
 			}
+
+			template<typename ForwardIterator, typename Result, typename... Args>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				sprout::container_traits<Result>::static_size == sizeof...(Args),
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			phase_spectrum_impl(
+				ForwardIterator first, ForwardIterator last, Result const& result,
+				typename sprout::container_traits<Result>::size_type size,
+				Args const&... args
+				)
+			{
+				return sprout::remake<Result>(result, sprout::size(result), args...);
+			}
+			template<typename ForwardIterator, typename Result, typename... Args>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				sprout::container_traits<Result>::static_size != sizeof...(Args),
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			phase_spectrum_impl(
+				ForwardIterator first, ForwardIterator last, Result const& result,
+				typename sprout::container_traits<Result>::size_type size,
+				Args const&... args
+				)
+			{
+				return first != last && sizeof...(Args) < size
+					? sprout::fixed::detail::phase_spectrum_impl(
+						sprout::next(first), last, result, size,
+						args..., sprout::phase_spectrum_value(*first)
+						)
+					: sprout::detail::container_complate(result, args...)
+					;
+			}
+			template<typename ForwardIterator, typename Result>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			phase_spectrum(
+				ForwardIterator first, ForwardIterator last, Result const& result,
+				void*
+				)
+			{
+				return sprout::fixed::detail::phase_spectrum_impl(first, last, result, sprout::size(result));
+			}
+
+			template<typename InputIterator, typename Result>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				sprout::is_fixed_container<Result>::value,
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			phase_spectrum(InputIterator first, InputIterator last, Result const& result) {
+				typedef typename std::iterator_traits<InputIterator>::iterator_category* category;
+				return sprout::fixed::detail::phase_spectrum(first, last, result, category());
+			}
+
+			template<typename InputIterator, typename Result>
+			inline SPROUT_CONSTEXPR typename std::enable_if<
+				!sprout::is_fixed_container<Result>::value,
+				typename sprout::fixed::result_of::algorithm<Result>::type
+			>::type
+			phase_spectrum(InputIterator first, InputIterator last, Result const& result) {
+				return sprout::remake<Result>(
+					result, sprout::size(result),
+					sprout::make_phase_spectrum_iterator(first),
+					sprout::make_phase_spectrum_iterator(last)
+					);
+			}
 		}	// namespace detail
 		//
 		// phase_spectrum
@@ -53,6 +125,12 @@ namespace sprout {
 		phase_spectrum(InputIterator first, InputIterator last, Result const& result) {
 			return sprout::fixed::detail::phase_spectrum(first, last, result);
 		}
+
+		template<typename Result, typename ForwardIterator>
+		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+		phase_spectrum(ForwardIterator first, ForwardIterator last) {
+			return sprout::fixed::phase_spectrum(first, last, sprout::pit<Result>());
+		}
 	}	// namespace fixed
 
 	using sprout::fixed::phase_spectrum;
diff --git a/sprout/numeric/dft/fixed/sawtooth.hpp b/sprout/numeric/dft/fixed/sawtooth.hpp
index ebbfe8de..b1eb153c 100644
--- a/sprout/numeric/dft/fixed/sawtooth.hpp
+++ b/sprout/numeric/dft/fixed/sawtooth.hpp
@@ -7,7 +7,10 @@
 #include <sprout/container/functions.hpp>
 #include <sprout/container/indexes.hpp>
 #include <sprout/algorithm/fixed/result_of.hpp>
+#include <sprout/pit.hpp>
+#include <sprout/math/comparison.hpp>
 #include <sprout/math/floor.hpp>
+#include <sprout/detail/container_complate.hpp>
 
 namespace sprout {
 	namespace fixed {
@@ -33,8 +36,7 @@ namespace sprout {
 			{
 				typedef typename sprout::container_traits<Container>::value_type value_type;
 				return sprout::remake<Container>(
-					cont,
-					size,
+					cont, size,
 					(Indexes >= offset && Indexes < offset + size
 						? amplitude * sprout::fixed::detail::sawtooth_value(frequency * value_type(Indexes) + phase)
 						: *sprout::next(sprout::internal_begin(cont), Indexes)
@@ -76,6 +78,17 @@ namespace sprout {
 		{
 			return sprout::fixed::detail::sawtooth(cont, frequency, amplitude, phase);
 		}
+
+		template<typename Container>
+		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Container>::type
+		sawtooth(
+			typename sprout::container_traits<Container>::value_type const& frequency = 1,
+			typename sprout::container_traits<Container>::value_type const& amplitude = 1,
+			typename sprout::container_traits<Container>::value_type const& phase = 0
+			)
+		{
+			return sprout::fixed::sawtooth(sprout::pit<Container>(), frequency, amplitude, phase);
+		}
 	}	// namespace fixed
 
 	using sprout::fixed::sawtooth;
diff --git a/sprout/numeric/dft/fixed/sinusoid.hpp b/sprout/numeric/dft/fixed/sinusoid.hpp
index a5585a82..3d4c09df 100644
--- a/sprout/numeric/dft/fixed/sinusoid.hpp
+++ b/sprout/numeric/dft/fixed/sinusoid.hpp
@@ -7,8 +7,11 @@
 #include <sprout/container/functions.hpp>
 #include <sprout/container/indexes.hpp>
 #include <sprout/algorithm/fixed/result_of.hpp>
+#include <sprout/pit.hpp>
+#include <sprout/math/comparison.hpp>
 #include <sprout/math/constants.hpp>
 #include <sprout/math/sin.hpp>
+#include <sprout/detail/container_complate.hpp>
 
 namespace sprout {
 	namespace fixed {
@@ -28,8 +31,7 @@ namespace sprout {
 				typedef typename sprout::container_traits<Container>::value_type value_type;
 				using sprout::sin;
 				return sprout::remake<Container>(
-					cont,
-					size,
+					cont, size,
 					(Indexes >= offset && Indexes < offset + size
 						? amplitude * sin(d * value_type(Indexes) + phase)
 						: *sprout::next(sprout::internal_begin(cont), Indexes)
@@ -71,6 +73,17 @@ namespace sprout {
 		{
 			return sprout::fixed::detail::sinusoid(cont, frequency, amplitude, phase);
 		}
+
+		template<typename Container>
+		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Container>::type
+		sinusoid(
+			typename sprout::container_traits<Container>::value_type const& frequency = 1,
+			typename sprout::container_traits<Container>::value_type const& amplitude = 1,
+			typename sprout::container_traits<Container>::value_type const& phase = 0
+			)
+		{
+			return sprout::fixed::sinusoid(sprout::pit<Container>(), frequency, amplitude, phase);
+		}
 	}	// namespace fixed
 
 	using sprout::fixed::sinusoid;
diff --git a/sprout/numeric/dft/fixed/spectrum.hpp b/sprout/numeric/dft/fixed/spectrum.hpp
index 33755dec..c32d8bb6 100644
--- a/sprout/numeric/dft/fixed/spectrum.hpp
+++ b/sprout/numeric/dft/fixed/spectrum.hpp
@@ -15,6 +15,12 @@ namespace sprout {
 		spectrum(InputIterator first, InputIterator last, Result const& result) {
 			return sprout::fixed::amplitude_spectrum(first, last, result);
 		}
+
+		template<typename Result, typename InputIterator>
+		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+		spectrum(InputIterator first, InputIterator last) {
+			return sprout::fixed::amplitude_spectrum<Result>(first, last);
+		}
 	}	// namespace fixed
 
 	using sprout::fixed::spectrum;
diff --git a/sprout/numeric/dft/fixed/square.hpp b/sprout/numeric/dft/fixed/square.hpp
index 94f9ff84..f6960b65 100644
--- a/sprout/numeric/dft/fixed/square.hpp
+++ b/sprout/numeric/dft/fixed/square.hpp
@@ -7,7 +7,10 @@
 #include <sprout/container/functions.hpp>
 #include <sprout/container/indexes.hpp>
 #include <sprout/algorithm/fixed/result_of.hpp>
+#include <sprout/pit.hpp>
+#include <sprout/math/comparison.hpp>
 #include <sprout/numeric/dft/fixed/sawtooth.hpp>
+#include <sprout/detail/container_complate.hpp>
 
 namespace sprout {
 	namespace fixed {
@@ -33,8 +36,7 @@ namespace sprout {
 			{
 				typedef typename sprout::container_traits<Container>::value_type value_type;
 				return sprout::remake<Container>(
-					cont,
-					size,
+					cont, size,
 					(Indexes >= offset && Indexes < offset + size
 						? amplitude * sprout::fixed::detail::square_value(frequency * value_type(Indexes) + phase, duty)
 						: *sprout::next(sprout::internal_begin(cont), Indexes)
@@ -79,6 +81,18 @@ namespace sprout {
 		{
 			return sprout::fixed::detail::square(cont, frequency, amplitude, phase, duty);
 		}
+
+		template<typename Container>
+		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Container>::type
+		square(
+			typename sprout::container_traits<Container>::value_type const& frequency = 1,
+			typename sprout::container_traits<Container>::value_type const& amplitude = 1,
+			typename sprout::container_traits<Container>::value_type const& phase = 0,
+			typename sprout::container_traits<Container>::value_type const& duty = 0.5
+			)
+		{
+			return sprout::fixed::square(sprout::pit<Container>(), frequency, amplitude, phase, duty);
+		}
 	}	// namespace fixed
 
 	using sprout::fixed::square;
diff --git a/sprout/numeric/dft/fixed/triangle.hpp b/sprout/numeric/dft/fixed/triangle.hpp
index 55e782f7..767ba216 100644
--- a/sprout/numeric/dft/fixed/triangle.hpp
+++ b/sprout/numeric/dft/fixed/triangle.hpp
@@ -7,9 +7,12 @@
 #include <sprout/container/functions.hpp>
 #include <sprout/container/indexes.hpp>
 #include <sprout/algorithm/fixed/result_of.hpp>
+#include <sprout/pit.hpp>
+#include <sprout/math/comparison.hpp>
 #include <sprout/math/sin.hpp>
 #include <sprout/math/asin.hpp>
 #include <sprout/math/constants.hpp>
+#include <sprout/detail/container_complate.hpp>
 
 namespace sprout {
 	namespace fixed {
@@ -36,8 +39,7 @@ namespace sprout {
 			{
 				typedef typename sprout::container_traits<Container>::value_type value_type;
 				return sprout::remake<Container>(
-					cont,
-					size,
+					cont, size,
 					(Indexes >= offset && Indexes < offset + size
 						? amplitude * sprout::fixed::detail::triangle_value(frequency * value_type(Indexes) + phase)
 						: *sprout::next(sprout::internal_begin(cont), Indexes)
@@ -79,6 +81,17 @@ namespace sprout {
 		{
 			return sprout::fixed::detail::triangle(cont, frequency, amplitude, phase);
 		}
+
+		template<typename Container>
+		inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Container>::type
+		triangle(
+			typename sprout::container_traits<Container>::value_type const& frequency = 1,
+			typename sprout::container_traits<Container>::value_type const& amplitude = 1,
+			typename sprout::container_traits<Container>::value_type const& phase = 0
+			)
+		{
+			return sprout::fixed::triangle(sprout::pit<Container>(), frequency, amplitude, phase);
+		}
 	}	// namespace fixed
 
 	using sprout::fixed::triangle;
diff --git a/sprout/numeric/dft/idft_element.hpp b/sprout/numeric/dft/idft_element.hpp
index 0543574a..9972a2d9 100644
--- a/sprout/numeric/dft/idft_element.hpp
+++ b/sprout/numeric/dft/idft_element.hpp
@@ -3,9 +3,9 @@
 
 #include <iterator>
 #include <sprout/config.hpp>
-#include <sprout/numeric/dft/detail/dft_element_gen.hpp>
 #include <sprout/math/constants.hpp>
 #include <sprout/iterator/operation.hpp>
+#include <sprout/numeric/dft/detail/dft_element_gen.hpp>
 
 namespace sprout {
 	namespace detail {
diff --git a/sprout/numeric/dft/modifying.hpp b/sprout/numeric/dft/modifying.hpp
new file mode 100644
index 00000000..180770ea
--- /dev/null
+++ b/sprout/numeric/dft/modifying.hpp
@@ -0,0 +1,8 @@
+#ifndef SPROUT_NUMERIC_DFT_MODIFYIING_HPP
+#define SPROUT_NUMERIC_DFT_MODIFYIING_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/numeric/dft/fixed.hpp>
+#include <sprout/numeric/dft/fit.hpp>
+
+#endif	// #ifndef SPROUT_NUMERIC_DFT_MODIFYIING_HPP
diff --git a/sprout/numeric/dft/non_modifying.hpp b/sprout/numeric/dft/non_modifying.hpp
new file mode 100644
index 00000000..9c95b2db
--- /dev/null
+++ b/sprout/numeric/dft/non_modifying.hpp
@@ -0,0 +1,10 @@
+#ifndef SPROUT_NUMERIC_DFT_NON_MODIFYIING_HPP
+#define SPROUT_NUMERIC_DFT_NON_MODIFYIING_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/numeric/dft/dft_element.hpp>
+#include <sprout/numeric/dft/idft_element.hpp>
+#include <sprout/numeric/dft/amplitude_spectrum_value.hpp>
+#include <sprout/numeric/dft/phase_spectrum_value.hpp>
+
+#endif	// #ifndef SPROUT_NUMERIC_DFT_NON_MODIFYIING_HPP
diff --git a/sprout/numeric/fit/adjacent_difference.hpp b/sprout/numeric/fit/adjacent_difference.hpp
index d31a5f6b..d8e02667 100644
--- a/sprout/numeric/fit/adjacent_difference.hpp
+++ b/sprout/numeric/fit/adjacent_difference.hpp
@@ -2,13 +2,14 @@
 #define SPROUT_NUMERIC_FIT_ADJACENT_DIFFERENCE_HPP
 
 #include <sprout/config.hpp>
+#include <sprout/iterator/distance.hpp>
 #include <sprout/container/traits.hpp>
 #include <sprout/container/functions.hpp>
 #include <sprout/numeric/fixed/adjacent_difference.hpp>
 #include <sprout/algorithm/fit/result_of.hpp>
 #include <sprout/sub_array.hpp>
-#include <sprout/iterator/operation.hpp>
 #include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
+#include <sprout/iterator/type_traits/is_iterator.hpp>
 
 namespace sprout {
 	namespace fit {
@@ -33,6 +34,7 @@ namespace sprout {
 		template<typename InputIterator, typename Result>
 		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
 		adjacent_difference(InputIterator first, InputIterator last, Result const& result) {
+			static_assert(sprout::is_forward_iterator<InputIterator>::value, "Sorry, not implemented.");
 			return sprout::fit::detail::adjacent_difference_impl(first, last, result, sprout::internal_begin_offset(result));
 		}
 
@@ -57,6 +59,7 @@ namespace sprout {
 		template<typename InputIterator, typename Result, typename BinaryOperation>
 		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
 		adjacent_difference(InputIterator first, InputIterator last, Result const& result, BinaryOperation binary_op) {
+			static_assert(sprout::is_forward_iterator<InputIterator>::value, "Sorry, not implemented.");
 			return sprout::fit::detail::adjacent_difference_impl(first, last, result, binary_op, sprout::internal_begin_offset(result));
 		}
 	}	// namespace fit
diff --git a/sprout/numeric/fit/partial_sum.hpp b/sprout/numeric/fit/partial_sum.hpp
index 033d24ac..64df4b3a 100644
--- a/sprout/numeric/fit/partial_sum.hpp
+++ b/sprout/numeric/fit/partial_sum.hpp
@@ -2,13 +2,14 @@
 #define SPROUT_NUMERIC_FIT_PARTIAL_SUM_HPP
 
 #include <sprout/config.hpp>
+#include <sprout/iterator/distance.hpp>
 #include <sprout/container/traits.hpp>
 #include <sprout/container/functions.hpp>
 #include <sprout/numeric/fixed/partial_sum.hpp>
 #include <sprout/algorithm/fit/result_of.hpp>
 #include <sprout/sub_array.hpp>
-#include <sprout/iterator/operation.hpp>
 #include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
+#include <sprout/iterator/type_traits/is_iterator.hpp>
 
 namespace sprout {
 	namespace fit {
@@ -33,6 +34,7 @@ namespace sprout {
 		template<typename InputIterator, typename Result>
 		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
 		partial_sum(InputIterator first, InputIterator last, Result const& result) {
+			static_assert(sprout::is_forward_iterator<InputIterator>::value, "Sorry, not implemented.");
 			return sprout::fit::detail::partial_sum_impl(first, last, result, sprout::internal_begin_offset(result));
 		}
 
@@ -57,6 +59,7 @@ namespace sprout {
 		template<typename InputIterator, typename Result, typename BinaryOperation>
 		inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
 		partial_sum(InputIterator first, InputIterator last, Result const& result, BinaryOperation binary_op) {
+			static_assert(sprout::is_forward_iterator<InputIterator>::value, "Sorry, not implemented.");
 			return sprout::fit::detail::partial_sum_impl(first, last, result, binary_op, sprout::internal_begin_offset(result));
 		}
 	}	// namespace fit
diff --git a/sprout/range/numeric/dft.hpp b/sprout/range/numeric/dft.hpp
index 0c05ae47..1ded06ba 100644
--- a/sprout/range/numeric/dft.hpp
+++ b/sprout/range/numeric/dft.hpp
@@ -2,10 +2,7 @@
 #define SPROUT_RANGE_NUMERIC_DFT_HPP
 
 #include <sprout/config.hpp>
-#include <sprout/range/numeric/dft/dft.hpp>
-#include <sprout/range/numeric/dft/idft.hpp>
-#include <sprout/range/numeric/dft/dft_element.hpp>
-#include <sprout/range/numeric/dft/idft_element.hpp>
-#include <sprout/range/numeric/dft/spectrum.hpp>
+#include <sprout/range/numeric/dft/non_modifying.hpp>
+#include <sprout/range/numeric/dft/modifying.hpp>
 
 #endif	// #ifndef SPROUT_RANGE_NUMERIC_DFT_HPP
diff --git a/sprout/range/numeric/dft/fit.hpp b/sprout/range/numeric/dft/fit.hpp
new file mode 100644
index 00000000..a6efc120
--- /dev/null
+++ b/sprout/range/numeric/dft/fit.hpp
@@ -0,0 +1,9 @@
+#ifndef SPROUT_RANGE_NUMERIC_DFT_FIT_HPP
+#define SPROUT_RANGE_NUMERIC_DFT_FIT_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/range/numeric/dft/fit/dft.hpp>
+#include <sprout/range/numeric/dft/fit/idft.hpp>
+#include <sprout/range/numeric/dft/fit/spectrum.hpp>
+
+#endif	// #ifndef SPROUT_RANGE_NUMERIC_DFT_FIT_HPP
diff --git a/sprout/range/numeric/dft/fit/amplitude_spectrum.hpp b/sprout/range/numeric/dft/fit/amplitude_spectrum.hpp
index ec69f189..b08e38f1 100644
--- a/sprout/range/numeric/dft/fit/amplitude_spectrum.hpp
+++ b/sprout/range/numeric/dft/fit/amplitude_spectrum.hpp
@@ -18,6 +18,12 @@ namespace sprout {
 			amplitude_spectrum(Input const& input, Result const& result) {
 				return sprout::fit::amplitude_spectrum(sprout::begin(input), sprout::end(input), result);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
+			amplitude_spectrum(Input const& input) {
+				return sprout::fit::amplitude_spectrum<Result>(sprout::begin(input), sprout::end(input));
+			}
 		}	// namespace fit
 	}	// namespace range
 }	// namespace sprout
diff --git a/sprout/range/numeric/dft/fit/dft.hpp b/sprout/range/numeric/dft/fit/dft.hpp
index c64a85ae..b1c5b5e6 100644
--- a/sprout/range/numeric/dft/fit/dft.hpp
+++ b/sprout/range/numeric/dft/fit/dft.hpp
@@ -18,6 +18,12 @@ namespace sprout {
 			dft(Input const& input, Result const& result) {
 				return sprout::fit::dft(sprout::begin(input), sprout::end(input), result);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
+			dft(Input const& input) {
+				return sprout::fit::dft<Result>(sprout::begin(input), sprout::end(input));
+			}
 		}	// namespace fit
 	}	// namespace range
 }	// namespace sprout
diff --git a/sprout/range/numeric/dft/fit/idft.hpp b/sprout/range/numeric/dft/fit/idft.hpp
index 84a86388..32ad8431 100644
--- a/sprout/range/numeric/dft/fit/idft.hpp
+++ b/sprout/range/numeric/dft/fit/idft.hpp
@@ -18,6 +18,12 @@ namespace sprout {
 			idft(Input const& input, Result const& result) {
 				return sprout::fit::idft(sprout::begin(input), sprout::end(input), result);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
+			idft(Input const& input) {
+				return sprout::fit::idft<Result>(sprout::begin(input), sprout::end(input));
+			}
 		}	// namespace fit
 	}	// namespace range
 }	// namespace sprout
diff --git a/sprout/range/numeric/dft/fit/phase_spectrum.hpp b/sprout/range/numeric/dft/fit/phase_spectrum.hpp
index 5661be5c..d633b2af 100644
--- a/sprout/range/numeric/dft/fit/phase_spectrum.hpp
+++ b/sprout/range/numeric/dft/fit/phase_spectrum.hpp
@@ -18,6 +18,12 @@ namespace sprout {
 			phase_spectrum(Input const& input, Result const& result) {
 				return sprout::fit::phase_spectrum(sprout::begin(input), sprout::end(input), result);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
+			phase_spectrum(Input const& input) {
+				return sprout::fit::phase_spectrum<Result>(sprout::begin(input), sprout::end(input));
+			}
 		}	// namespace fit
 	}	// namespace range
 }	// namespace sprout
diff --git a/sprout/range/numeric/dft/fit/spectrum.hpp b/sprout/range/numeric/dft/fit/spectrum.hpp
index 1bb12833..f5c9e4f9 100644
--- a/sprout/range/numeric/dft/fit/spectrum.hpp
+++ b/sprout/range/numeric/dft/fit/spectrum.hpp
@@ -18,6 +18,12 @@ namespace sprout {
 			spectrum(Input const& input, Result const& result) {
 				return sprout::fit::spectrum(sprout::begin(input), sprout::end(input), result);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
+			spectrum(Input const& input) {
+				return sprout::fit::spectrum<Result>(sprout::begin(input), sprout::end(input));
+			}
 		}	// namespace fit
 	}	// namespace range
 }	// namespace sprout
diff --git a/sprout/range/numeric/dft/fixed.hpp b/sprout/range/numeric/dft/fixed.hpp
new file mode 100644
index 00000000..76dc46b1
--- /dev/null
+++ b/sprout/range/numeric/dft/fixed.hpp
@@ -0,0 +1,9 @@
+#ifndef SPROUT_RANGE_NUMERIC_DFT_FIXED_HPP
+#define SPROUT_RANGE_NUMERIC_DFT_FIXED_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/range/numeric/dft/fixed/dft.hpp>
+#include <sprout/range/numeric/dft/fixed/idft.hpp>
+#include <sprout/range/numeric/dft/fixed/spectrum.hpp>
+
+#endif	// #ifndef SPROUT_RANGE_NUMERIC_DFT_FIXED_HPP
diff --git a/sprout/range/numeric/dft/fixed/amplitude_spectrum.hpp b/sprout/range/numeric/dft/fixed/amplitude_spectrum.hpp
index 8e500c42..702e6c93 100644
--- a/sprout/range/numeric/dft/fixed/amplitude_spectrum.hpp
+++ b/sprout/range/numeric/dft/fixed/amplitude_spectrum.hpp
@@ -18,6 +18,12 @@ namespace sprout {
 			amplitude_spectrum(Input const& input, Result const& result) {
 				return sprout::fixed::amplitude_spectrum(sprout::begin(input), sprout::end(input), result);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			amplitude_spectrum(Input const& input) {
+				return sprout::fixed::amplitude_spectrum<Result>(sprout::begin(input), sprout::end(input));
+			}
 		}	// namespace fixed
 
 		using sprout::range::fixed::amplitude_spectrum;
diff --git a/sprout/range/numeric/dft/fixed/dft.hpp b/sprout/range/numeric/dft/fixed/dft.hpp
index ebcf67ae..da78cee1 100644
--- a/sprout/range/numeric/dft/fixed/dft.hpp
+++ b/sprout/range/numeric/dft/fixed/dft.hpp
@@ -18,6 +18,12 @@ namespace sprout {
 			dft(Input const& input, Result const& result) {
 				return sprout::fixed::dft(sprout::begin(input), sprout::end(input), result);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			dft(Input const& input) {
+				return sprout::fixed::dft<Result>(sprout::begin(input), sprout::end(input));
+			}
 		}	// namespace fixed
 
 		using sprout::range::fixed::dft;
diff --git a/sprout/range/numeric/dft/fixed/idft.hpp b/sprout/range/numeric/dft/fixed/idft.hpp
index 3b7620c1..52fce1ec 100644
--- a/sprout/range/numeric/dft/fixed/idft.hpp
+++ b/sprout/range/numeric/dft/fixed/idft.hpp
@@ -18,6 +18,12 @@ namespace sprout {
 			idft(Input const& input, Result const& result) {
 				return sprout::fixed::idft(sprout::begin(input), sprout::end(input), result);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			idft(Input const& input) {
+				return sprout::fixed::idft<Result>(sprout::begin(input), sprout::end(input));
+			}
 		}	// namespace fixed
 
 		using sprout::range::fixed::idft;
diff --git a/sprout/range/numeric/dft/fixed/phase_spectrum.hpp b/sprout/range/numeric/dft/fixed/phase_spectrum.hpp
index 4b3bb15f..28556e2e 100644
--- a/sprout/range/numeric/dft/fixed/phase_spectrum.hpp
+++ b/sprout/range/numeric/dft/fixed/phase_spectrum.hpp
@@ -18,6 +18,12 @@ namespace sprout {
 			phase_spectrum(Input const& input, Result const& result) {
 				return sprout::fixed::phase_spectrum(sprout::begin(input), sprout::end(input), result);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			phase_spectrum(Input const& input) {
+				return sprout::fixed::phase_spectrum<Result>(sprout::begin(input), sprout::end(input));
+			}
 		}	// namespace fixed
 
 		using sprout::range::fixed::phase_spectrum;
diff --git a/sprout/range/numeric/dft/fixed/spectrum.hpp b/sprout/range/numeric/dft/fixed/spectrum.hpp
index f3200c27..df1db2d3 100644
--- a/sprout/range/numeric/dft/fixed/spectrum.hpp
+++ b/sprout/range/numeric/dft/fixed/spectrum.hpp
@@ -18,6 +18,12 @@ namespace sprout {
 			spectrum(Input const& input, Result const& result) {
 				return sprout::fixed::spectrum(sprout::begin(input), sprout::end(input), result);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			spectrum(Input const& input) {
+				return sprout::fixed::spectrum<Result>(sprout::begin(input), sprout::end(input));
+			}
 		}	// namespace fixed
 
 		using sprout::range::fixed::spectrum;
diff --git a/sprout/range/numeric/dft/modifying.hpp b/sprout/range/numeric/dft/modifying.hpp
new file mode 100644
index 00000000..7f609630
--- /dev/null
+++ b/sprout/range/numeric/dft/modifying.hpp
@@ -0,0 +1,8 @@
+#ifndef SPROUT_RANGE_NUMERIC_DFT_MODIFYIING_HPP
+#define SPROUT_RANGE_NUMERIC_DFT_MODIFYIING_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/range/numeric/dft/fixed.hpp>
+#include <sprout/range/numeric/dft/fit.hpp>
+
+#endif	// #ifndef SPROUT_RANGE_NUMERIC_DFT_MODIFYIING_HPP
diff --git a/sprout/range/numeric/dft/non_modifying.hpp b/sprout/range/numeric/dft/non_modifying.hpp
new file mode 100644
index 00000000..48755f86
--- /dev/null
+++ b/sprout/range/numeric/dft/non_modifying.hpp
@@ -0,0 +1,8 @@
+#ifndef SPROUT_RANGE_NUMERIC_DFT_NON_MODIFYIING_HPP
+#define SPROUT_RANGE_NUMERIC_DFT_NON_MODIFYIING_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/range/numeric/dft/dft_element.hpp>
+#include <sprout/range/numeric/dft/idft_element.hpp>
+
+#endif	// #ifndef SPROUT_RANGE_NUMERIC_DFT_NON_MODIFYIING_HPP
diff --git a/sprout/range/numeric/fit/adjacent_difference.hpp b/sprout/range/numeric/fit/adjacent_difference.hpp
index 5b51f8f8..6715c9a4 100644
--- a/sprout/range/numeric/fit/adjacent_difference.hpp
+++ b/sprout/range/numeric/fit/adjacent_difference.hpp
@@ -23,6 +23,17 @@ namespace sprout {
 			adjacent_difference(Input const& input, Result const& result, BinaryOperation binary_op) {
 				return sprout::fit::adjacent_difference(sprout::begin(input), sprout::end(input), result, binary_op);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
+			adjacent_difference(Input const& input) {
+				return sprout::fit::adjacent_difference<Result>(sprout::begin(input), sprout::end(input));
+			}
+			template<typename Result, typename Input, typename BinaryOperation>
+			inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
+			adjacent_difference(Input const& input, BinaryOperation binary_op) {
+				return sprout::fit::adjacent_difference<Result>(sprout::begin(input), sprout::end(input), binary_op);
+			}
 		}	// namespace fit
 	}	// namespace range
 }	// namespace sprout
diff --git a/sprout/range/numeric/fit/partial_sum.hpp b/sprout/range/numeric/fit/partial_sum.hpp
index 608aec9d..8b2778dd 100644
--- a/sprout/range/numeric/fit/partial_sum.hpp
+++ b/sprout/range/numeric/fit/partial_sum.hpp
@@ -23,6 +23,17 @@ namespace sprout {
 			partial_sum(Input const& input, Result const& result, BinaryOperation binary_op) {
 				return sprout::fit::partial_sum(sprout::begin(input), sprout::end(input), result, binary_op);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
+			partial_sum(Input const& input) {
+				return sprout::fit::partial_sum<Result>(sprout::begin(input), sprout::end(input));
+			}
+			template<typename Result, typename Input, typename BinaryOperation>
+			inline SPROUT_CONSTEXPR typename sprout::fit::result_of::algorithm<Result>::type
+			partial_sum(Input const& input, BinaryOperation binary_op) {
+				return sprout::fit::partial_sum<Result>(sprout::begin(input), sprout::end(input), binary_op);
+			}
 		}	// namespace fit
 	}	// namespace range
 }	// namespace sprout
diff --git a/sprout/range/numeric/fixed/adjacent_difference.hpp b/sprout/range/numeric/fixed/adjacent_difference.hpp
index 3e978dd0..7d7d6508 100644
--- a/sprout/range/numeric/fixed/adjacent_difference.hpp
+++ b/sprout/range/numeric/fixed/adjacent_difference.hpp
@@ -23,6 +23,17 @@ namespace sprout {
 			adjacent_difference(Input const& input, Result const& result, BinaryOperation binary_op) {
 				return sprout::fixed::adjacent_difference(sprout::begin(input), sprout::end(input), result, binary_op);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			adjacent_difference(Input const& input) {
+				return sprout::fixed::adjacent_difference<Result>(sprout::begin(input), sprout::end(input));
+			}
+			template<typename Result, typename Input, typename BinaryOperation>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			adjacent_difference(Input const& input, BinaryOperation binary_op) {
+				return sprout::fixed::adjacent_difference<Result>(sprout::begin(input), sprout::end(input), binary_op);
+			}
 		}	// namespace fixed
 
 		using sprout::range::fixed::adjacent_difference;
diff --git a/sprout/range/numeric/fixed/partial_sum.hpp b/sprout/range/numeric/fixed/partial_sum.hpp
index 29f94b1f..41d46685 100644
--- a/sprout/range/numeric/fixed/partial_sum.hpp
+++ b/sprout/range/numeric/fixed/partial_sum.hpp
@@ -23,6 +23,17 @@ namespace sprout {
 			partial_sum(Input const& input, Result const& result, BinaryOperation binary_op) {
 				return sprout::fixed::partial_sum(sprout::begin(input), sprout::end(input), result, binary_op);
 			}
+
+			template<typename Result, typename Input>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			partial_sum(Input const& input) {
+				return sprout::fixed::partial_sum<Result>(sprout::begin(input), sprout::end(input));
+			}
+			template<typename Result, typename Input, typename BinaryOperation>
+			inline SPROUT_CONSTEXPR typename sprout::fixed::result_of::algorithm<Result>::type
+			partial_sum(Input const& input, BinaryOperation binary_op) {
+				return sprout::fixed::partial_sum<Result>(sprout::begin(input), sprout::end(input), binary_op);
+			}
 		}	// namespace fixed
 
 		using sprout::range::fixed::partial_sum;