From 5802e2fb1162ea137a2b37526e9bcbd5244f4dcc Mon Sep 17 00:00:00 2001
From: Gathros <6323830+Gathros@users.noreply.github.com>
Date: Thu, 3 Jan 2019 11:37:02 +0000
Subject: [PATCH 1/2] adding fftw3 test to fft
---
contents/cooley_tukey/code/c/fft.c | 27 +++++++++++++++++++++++++--
1 file changed, 25 insertions(+), 2 deletions(-)
diff --git a/contents/cooley_tukey/code/c/fft.c b/contents/cooley_tukey/code/c/fft.c
index 839507df6..90691f373 100644
--- a/contents/cooley_tukey/code/c/fft.c
+++ b/contents/cooley_tukey/code/c/fft.c
@@ -4,6 +4,23 @@
#include <stdlib.h>
#include <string.h>
#include <time.h>
+#include <fftw3.h>
+
+void fft(double complex *x, int n) {
+ double complex y[n];
+ memset(y, 0, sizeof(y));
+ fftw_plan p;
+
+ p = fftw_plan_dft_1d(n, (fftw_complex*)x, (fftw_complex*)y,
+ FFTW_FORWARD, FFTW_ESTIMATE);
+
+ fftw_execute(p);
+ fftw_destroy_plan(p);
+
+ for (size_t i = 0; i < n; ++i) {
+ x[i] = y[i] / sqrt((double)n);
+ }
+}
void dft(double complex *X, const size_t N) {
double complex tmp[N];
@@ -79,8 +96,12 @@ void iterative_cooley_tukey(double complex *X, size_t N) {
void approx(double complex *X, double complex *Y, size_t N) {
for (size_t i = 0; i < N; ++i) {
- printf("%f\n", cabs(X[i]) - cabs(Y[i]));
+ if (cabs(X[i]) - cabs(Y[i]) > 1E-5) {
+ printf("This is not approximate.\n");
+ return;
+ }
}
+ printf("This is approximate.\n");
}
int main() {
@@ -92,10 +113,12 @@ int main() {
z[i] = x[i];
}
+ fft(x, 64);
cooley_tukey(y, 64);
iterative_cooley_tukey(z, 64);
- approx(y, z, 64);
+ approx(x, y, 64);
+ approx(x, z, 64);
return 0;
}
From 01e43f80acd1a48116646d56a88ef3acef56d0c5 Mon Sep 17 00:00:00 2001
From: Gathros <6323830+Gathros@users.noreply.github.com>
Date: Thu, 3 Jan 2019 11:39:47 +0000
Subject: [PATCH 2/2] updating cooley_tukey.md
---
contents/cooley_tukey/cooley_tukey.md | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/contents/cooley_tukey/cooley_tukey.md b/contents/cooley_tukey/cooley_tukey.md
index fc51aa459..27d74e6da 100644
--- a/contents/cooley_tukey/cooley_tukey.md
+++ b/contents/cooley_tukey/cooley_tukey.md
@@ -72,7 +72,7 @@ For some reason, though, putting code to this transformation really helped me fi
{% sample lang="jl" %}
[import:4-13, lang:"julia"](code/julia/fft.jl)
{% sample lang="c" %}
-[import:8-19, lang:"c"](code/c/fft.c)
+[import:25-35, lang:"c"](code/c/fft.c)
{% sample lang="clj" %}
[import:15-30, lang:"clojure"](code/clojure/fft.clj)
{% sample lang="cpp" %}
@@ -121,7 +121,7 @@ In the end, the code looks like:
{% sample lang="jl" %}
[import:16-32, lang:"julia"](code/julia/fft.jl)
{% sample lang="c" %}
-[import:20-39, lang:"c"](code/c/fft.c)
+[import:37-56, lang:"c"](code/c/fft.c)
{% sample lang="clj" %}
[import:31-58, lang:"clojure"](code/clojure/fft.clj)
{% sample lang="cpp" %}