Changeset 16107 for trunk/Ohana/src/opihi/lib.data/fftold.c

Timestamp:

Jan 17, 2008, 8:41:08 AM (19 years ago)

Author:

eugene

Message:

converting fft and fftn to code from Jones, with Magnier version of multi-dim

File:

• trunk/Ohana/src/opihi/lib.data/fftold.c (modified) (1 diff)

trunk/Ohana/src/opihi/lib.data/fftold.c

@@ -49 +49 @@
     mmax = istep;
   }
-}
-
-void fftold_Nindices (float *Data, int N, int isign) {
-
-  int n,ifp1,m,j,ipf2,i;
-  double wtemp,wr,wpr,wpi,wi,theta;
-  float tempr,tempi, *data;
-
-  data = Data;
-  n = N << 1;
-
-  ip1 = 2;
-  ip2 = n;
-  i2rev = 0;
-  for (i2 = 0; i2 < ip2; i2 += ip1) {
-    if (i2 < i2ref) {
-      FSWAP (data[i2rev], data[i2]);
-      FSWAP (data[i2rev+1], data[i2+1]);
-    }
-    ibit = ip2 >> 1;
-    while (ibit >= ip1 && i2rev >= ibit) {
-      i2rev -= ibit;
-      ibit >>= 1;
-    }
-    i2rev += ibit;
-  }
-
-  ifp1 = 2;
-  while (ifp1 < ip2) {
-    ifp2 = ifp1 << 1;
-    theta = isign*6.28318530717959 / (2*ifp1/ip1);
-    wtemp = sin(0.5*theta);
-    wpr = -2.0*wtemp*wtemp;
-    wpi = sin(theta);
-    wr = 1.0;
-    wi = 0.0;
-    for (i3 = 0; i3 < ifp1; i3+=ip1) {
-      // in the N-d version, this loop is broken into two loops
-      for (i1 = i3; i1 < n; i1+=ipf2) {
-        k1 = i1;
-        k2 = k1 + ifp1;
-        tempr = wr*data[k2] - wi*data[k2+1];
-        tempi = wr*data[k2+1] + wi*data[k2];
-        data[k2] = data[k1] - tempr;
-        data[k2+1] = data[k1+1] - tempi;
-        data[k1] += tempr;
-        data[k1+1] += tempi;
-      }
-      wr = (wtemp = wr)*wpr - wi*wpi+wr;
-      wi = wi*wpr + wtemp*wpi + wi;
-    }
-    ifp1 = ifp2;
-  }
-
 }