mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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216 lines
7.3 KiB
C++
216 lines
7.3 KiB
C++
#ifndef SPROUT_RANDOM_LINEAR_CONGRUENTIAL_HPP
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#define SPROUT_RANDOM_LINEAR_CONGRUENTIAL_HPP
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#include <cstdint>
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#include <limits>
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#include <ios>
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/random/detail/const_mod.hpp>
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#include <sprout/random/random_result.hpp>
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#include <sprout/math/comparison.hpp>
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#include <sprout/assert.hpp>
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namespace sprout {
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namespace random {
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//
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// linear_congruential_engine
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//
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template<typename UIntType, UIntType a, UIntType c, UIntType m>
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class linear_congruential_engine {
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static_assert(std::numeric_limits<UIntType>::is_integer, "std::numeric_limits<UIntType>::is_integer");
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static_assert(m == 0 || a < m, "m == 0 || a < m");
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static_assert(m == 0 || c < m, "m == 0 || c < m");
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public:
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typedef UIntType result_type;
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private:
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struct private_constructor_tag {};
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public:
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SPROUT_STATIC_CONSTEXPR UIntType multiplier = a;
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SPROUT_STATIC_CONSTEXPR UIntType increment = c;
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SPROUT_STATIC_CONSTEXPR UIntType modulus = m;
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SPROUT_STATIC_CONSTEXPR UIntType default_seed = 1;
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public:
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static SPROUT_CONSTEXPR result_type static_min() SPROUT_NOEXCEPT {
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return c == 0 ? 1 : 0;
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}
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static SPROUT_CONSTEXPR result_type static_max() SPROUT_NOEXCEPT {
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return m - 1;
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}
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private:
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static SPROUT_CONSTEXPR UIntType init_seed_3(UIntType const& x0) {
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return SPROUT_ASSERT(sprout::math::greater_equal(x0, static_min())), SPROUT_ASSERT(x0 <= static_max()), x0;
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}
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static SPROUT_CONSTEXPR UIntType init_seed_2(UIntType const& x0) {
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return init_seed_3(increment == 0 && x0 == 0 ? 1 : x0);
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}
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static SPROUT_CONSTEXPR UIntType init_seed_1(UIntType const& x0) {
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return init_seed_2(x0 <= 0 && x0 != 0 ? x0 + modulus : x0);
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}
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static SPROUT_CONSTEXPR UIntType init_seed(UIntType const& x0) {
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return init_seed_1(modulus == 0 ? x0 : x0 % modulus);
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}
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private:
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UIntType x_;
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private:
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SPROUT_CONSTEXPR linear_congruential_engine(UIntType const& x, private_constructor_tag)
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: x_(x)
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{}
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SPROUT_CONSTEXPR sprout::random::random_result<linear_congruential_engine> generate(result_type result) const {
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return sprout::random::random_result<linear_congruential_engine>(
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result,
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linear_congruential_engine(result, private_constructor_tag())
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);
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}
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public:
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SPROUT_CONSTEXPR linear_congruential_engine()
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: x_(init_seed(default_seed))
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{}
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explicit SPROUT_CONSTEXPR linear_congruential_engine(UIntType const& x0)
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: x_(init_seed(x0))
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{}
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SPROUT_CONSTEXPR result_type min() const SPROUT_NOEXCEPT {
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return static_min();
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}
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SPROUT_CONSTEXPR result_type max() const SPROUT_NOEXCEPT {
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return static_max();
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}
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SPROUT_CONSTEXPR sprout::random::random_result<linear_congruential_engine> operator()() const {
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return generate(sprout::random::detail::const_mod<UIntType, m>::mult_add(a, x_, c));
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}
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friend SPROUT_CONSTEXPR bool operator==(linear_congruential_engine const& lhs, linear_congruential_engine const& rhs) SPROUT_NOEXCEPT {
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return lhs.x_ == rhs.x_;
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}
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friend SPROUT_CONSTEXPR bool operator!=(linear_congruential_engine const& lhs, linear_congruential_engine const& rhs) SPROUT_NOEXCEPT {
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return !(lhs == rhs);
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}
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template<typename Elem, typename Traits>
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friend std::basic_istream<Elem, Traits>& operator>>(
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std::basic_istream<Elem, Traits>& lhs,
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linear_congruential_engine& rhs
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)
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{
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UIntType x;
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if (lhs >> x) {
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if (sprout::math::greater_equal(x, static_min()) && x <= static_max()) {
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rhs.x_ = x;
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} else {
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lhs.setstate(std::ios_base::failbit);
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}
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}
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return lhs;
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}
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template<typename Elem, typename Traits>
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friend std::basic_ostream<Elem, Traits>& operator<<(
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std::basic_ostream<Elem, Traits>& lhs,
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linear_congruential_engine const& rhs
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)
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{
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return lhs << rhs.x_;
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}
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};
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template<typename UIntType, UIntType a, UIntType c, UIntType m>
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SPROUT_CONSTEXPR_OR_CONST UIntType sprout::random::linear_congruential_engine<UIntType, a, c, m>::multiplier;
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template<typename UIntType, UIntType a, UIntType c, UIntType m>
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SPROUT_CONSTEXPR_OR_CONST UIntType sprout::random::linear_congruential_engine<UIntType, a, c, m>::increment;
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template<typename UIntType, UIntType a, UIntType c, UIntType m>
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SPROUT_CONSTEXPR_OR_CONST UIntType sprout::random::linear_congruential_engine<UIntType, a, c, m>::modulus;
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template<typename UIntType, UIntType a, UIntType c, UIntType m>
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SPROUT_CONSTEXPR_OR_CONST UIntType sprout::random::linear_congruential_engine<UIntType, a, c, m>::default_seed;
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//
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// minstd_rand0
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//
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typedef sprout::random::linear_congruential_engine<std::uint32_t, 16807, 0, 2147483647> minstd_rand0;
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//
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// minstd_rand
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//
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typedef sprout::random::linear_congruential_engine<std::uint32_t, 48271, 0, 2147483647> minstd_rand;
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//
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// rand48
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//
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class rand48 {
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public:
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typedef std::uint32_t result_type;
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private:
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struct private_constructor_tag {};
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typedef sprout::random::linear_congruential_engine<
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std::uint64_t,
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std::uint64_t(0xDEECE66DUL) | (std::uint64_t(0x5) << 32),
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0xB,
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std::uint64_t(1) << 48
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> lcf_type;
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private:
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static SPROUT_CONSTEXPR result_type static_min() {
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return 0;
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}
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static SPROUT_CONSTEXPR result_type static_max() {
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return 0x7FFFFFFF;
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}
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static SPROUT_CONSTEXPR std::uint64_t cnv(std::uint32_t x) {
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return (static_cast<std::uint64_t>(x) << 16) | 0x330e;
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}
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private:
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lcf_type lcf_;
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private:
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SPROUT_CONSTEXPR rand48(lcf_type const& lcf, private_constructor_tag)
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: lcf_(lcf)
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{}
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SPROUT_CONSTEXPR sprout::random::random_result<rand48> generate(
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sprout::random::random_result<lcf_type> const& lcf_result
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) const
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{
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return sprout::random::random_result<rand48>(
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lcf_result.result() >> 17,
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rand48(lcf_result.engine(), private_constructor_tag())
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);
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}
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public:
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SPROUT_CONSTEXPR rand48()
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: lcf_(cnv(static_cast<std::uint32_t>(1)))
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{}
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explicit SPROUT_CONSTEXPR rand48(result_type const& x0)
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: lcf_(cnv(x0))
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{}
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SPROUT_CONSTEXPR result_type min() const {
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return static_min();
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}
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SPROUT_CONSTEXPR result_type max() const {
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return static_max();
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}
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SPROUT_CONSTEXPR sprout::random::random_result<rand48> operator()() const {
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return generate(lcf_());
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}
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friend SPROUT_CONSTEXPR bool operator==(rand48 const& lhs, rand48 const& rhs) {
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return lhs.lcf_ == rhs.lcf_;
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}
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friend SPROUT_CONSTEXPR bool operator!=(rand48 const& lhs, rand48 const& rhs) {
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return !(lhs == rhs);
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}
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template<typename Elem, typename Traits>
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friend std::basic_istream<Elem, Traits>& operator>>(
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std::basic_istream<Elem, Traits>& lhs,
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rand48& rhs
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)
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{
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return lhs >> rhs.lcf_;
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}
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template<typename Elem, typename Traits>
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friend std::basic_ostream<Elem, Traits>& operator<<(
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std::basic_ostream<Elem, Traits>& lhs,
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rand48 const& rhs
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)
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{
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return lhs << rhs.lcf_;
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}
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};
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} // namespace random
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using sprout::random::linear_congruential_engine;
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using sprout::random::minstd_rand0;
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using sprout::random::minstd_rand;
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using sprout::random::rand48;
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} // namespace sprout
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#endif // #ifndef SPROUT_RANDOM_LINEAR_CONGRUENTIAL_HPP
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