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fix fft implementation

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bolero-MURAKAMI 2014-04-18 19:33:48 +09:00
parent 07b5f69ebb
commit d1fc657c1f
5 changed files with 72 additions and 17 deletions
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36
sprout/numeric/fft/fft.hpp
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@ -51,10 +51,14 @@ namespace sprout {
first[j] += first[j1];
value_type x3 = first[j3] - first[j2];
first[j2] += first[j3];
real(first[j1]) = real(x1) - imag(x3);
imag(first[j1]) = imag(x1) + real(x3);
real(first[j3]) = real(x1) + imag(x3);
imag(first[j3]) = imag(x1) - real(x3);
first[j1] = value_type(
real(x1) - imag(x3),
imag(x1) + real(x3)
);
first[j3] = value_type(
real(x1) + imag(x3),
imag(x1) - real(x3)
);
}
}
if (m == size) {
@ -73,12 +77,16 @@ namespace sprout {
first[j2] += first[j3];
elem_type x0r = real(x1) - imag(x3);
elem_type x0i = imag(x1) + real(x3);
real(first[j1]) = w1r * (x0r + x0i);
imag(first[j1]) = w1r * (x0i - x0r);
first[j1] = value_type(
w1r * (x0r + x0i),
w1r * (x0i - x0r)
);
x0r = real(x1) + imag(x3);
x0i = imag(x1) - real(x3);
real(first[j3]) = w1r * (-x0r + x0i);
imag(first[j3]) = w1r * (-x0i - x0r);
first[j3] = value_type(
w1r * (-x0r + x0i),
w1r * (-x0i - x0r)
);
}
}
for (difference_type i = 2 * m; i < size; i += m) {
@ -99,12 +107,16 @@ namespace sprout {
first[j2] += first[j3];
elem_type x0r = real(x1) - imag(x3);
elem_type x0i = imag(x1) + real(x3);
real(first[j1]) = w1r * x0r - w1i * x0i;
imag(first[j1]) = w1r * x0i + w1i * x0r;
first[j1] = value_type(
w1r * x0r - w1i * x0i,
w1r * x0i + w1i * x0r
);
x0r = real(x1) + imag(x3);
x0i = imag(x1) - real(x3);
real(first[j3]) = w3r * x0r - w3i * x0i;
imag(first[j3]) = w3r * x0i + w3i * x0r;
first[j3] = value_type(
w3r * x0r - w3i * x0i,
w3r * x0i + w3i * x0r
);
}
}
}