diff ext/kissfft/test/test_vs_dft.c @ 184:76ec2365b250

Bring in kissfft into this repo (formerly a subrepo, but the remote is not responding)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ext/kissfft/test/test_vs_dft.c	Tue Jul 21 07:34:15 2015 +0100
@@ -0,0 +1,74 @@
+#include "kiss_fft.h"
+
+
+void check(kiss_fft_cpx  * in,kiss_fft_cpx  * out,int nfft,int isinverse)
+{
+    int bin,k;
+    double errpow=0,sigpow=0;
+    
+    for (bin=0;bin<nfft;++bin) {
+        double ansr = 0;
+        double ansi = 0;
+        double difr;
+        double difi;
+
+        for (k=0;k<nfft;++k) {
+            double phase = -2*M_PI*bin*k/nfft;
+            double re = cos(phase);
+            double im = sin(phase);
+            if (isinverse)
+                im = -im;
+
+#ifdef FIXED_POINT
+            re /= nfft;
+            im /= nfft;
+#endif            
+
+            ansr += in[k].r * re - in[k].i * im;
+            ansi += in[k].r * im + in[k].i * re;
+        }
+        difr = ansr - out[bin].r;
+        difi = ansi - out[bin].i;
+        errpow += difr*difr + difi*difi;
+        sigpow += ansr*ansr+ansi*ansi;
+    }
+    printf("nfft=%d inverse=%d,snr = %f\n",nfft,isinverse,10*log10(sigpow/errpow) );
+}
+
+void test1d(int nfft,int isinverse)
+{
+    size_t buflen = sizeof(kiss_fft_cpx)*nfft;
+
+    kiss_fft_cpx  * in = (kiss_fft_cpx*)malloc(buflen);
+    kiss_fft_cpx  * out= (kiss_fft_cpx*)malloc(buflen);
+    kiss_fft_cfg  cfg = kiss_fft_alloc(nfft,isinverse,0,0);
+    int k;
+
+    for (k=0;k<nfft;++k) {
+        in[k].r = (rand() % 65536) - 32768;
+        in[k].i = (rand() % 65536) - 32768;
+    }
+
+    kiss_fft(cfg,in,out);
+
+    check(in,out,nfft,isinverse);
+
+    free(in);
+    free(out);
+    free(cfg);
+}
+
+int main(int argc,char ** argv)
+{
+    if (argc>1) {
+        int k;
+        for (k=1;k<argc;++k) {
+            test1d(atoi(argv[k]),0);
+            test1d(atoi(argv[k]),1);
+        }
+    }else{
+        test1d(32,0);
+        test1d(32,1);
+    }
+    return 0;
+}