idgt_fac.c

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#include "config.h"
#ifdef HAVE_COMPLEX_H
#include <complex.h>
#endif
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include "fftw3.h"
#include "dgt.h"

void idgt_fac(ltfat_complex *cin, ltfat_complex *gf, const int L, const int W,
	     const int R, const int a, const int M, ltfat_complex *f)
{

   /*  --------- initial declarations -------------- */

   int b, N, c, d, p, q, h_a, h_m;
   
   ltfat_complex *gbase, *fbase, *cbase;

   int l, k, r, s, u, w, rw, nm, mm, km;
   int ld1, ld2, ld3;

   div_t domod;

   fftw_plan p_before, p_after;
   ltfat_complex *ff, *cf;
   
   /*  ----------- calculation of parameters and plans -------- */

   b=L/M;
   N=L/a;
   
   c=gcd(a, M,&h_a, &h_m);
   p=a/c;
   q=M/c;
   d=b/p;

   h_a=-h_a;

   ff = (ltfat_complex*)ltfat_malloc(L*W*sizeof(ltfat_complex));
   cf = (ltfat_complex*)ltfat_malloc(c*d*q*q*W*R*sizeof(ltfat_complex));

   /* Create plans. In-place. */   
   p_before = fftw_plan_many_dft(1, &d, c*p*q*W,
				 ff, NULL,
				 c*p*q*W, 1,
				 ff, NULL,
				 c*p*q*W, 1,
				 FFTW_BACKWARD, FFTW_OPTITYPE);


   p_after = fftw_plan_many_dft(1, &d, c*q*q*W*R,
				cf, NULL,
				c*q*q*W*R, 1,
				cf, NULL,
				c*q*q*W*R, 1,
				FFTW_FORWARD, FFTW_OPTITYPE);
   


   /* -------- compute coefficient factorization ----------- */

   /* Leading dimensions of the 4dim array. */
   ld1=q*R;
   ld2=q*R*q*W;
   ld3=c*q*R*q*W;
   
   for (rw=0;rw<R;rw++)
   {
      for (w=0;w<W;w++)
      {
	 for (s=0;s<d;s++)
	 {
	    for (l=0;l<q;l++)
	    {
	       for (u=0;u<q;u++)
	       {	       
		  /*Add N to make sure it is positive */
		  domod= div(u+s*q-l*h_a+N*M,N);
		  for (r=0;r<c;r++)
		  {	
#ifdef HAVE_COMPLEX_H	  
		     cf[u+rw*q+(l+q*w)*ld1+r*ld2+s*ld3]    = cin[r+l*c+domod.rem*M+rw*M*N+w*M*N*R];
#else
		     cf[u+rw*q+(l+q*w)*ld1+r*ld2+s*ld3][0] = cin[r+l*c+domod.rem*M+rw*M*N+w*M*N*R][0];
		     cf[u+rw*q+(l+q*w)*ld1+r*ld2+s*ld3][1] = cin[r+l*c+domod.rem*M+rw*M*N+w*M*N*R][1];
#endif
		  }
	       }
	    }
	 }
      }           
   }

   /* Do fft of length d */
   fftw_execute(p_after);


   /* -------- compute matrix multiplication ---------- */
   

   /* Do the matmul  */
   for (r=0;r<c;r++)
   {
      for (s=0;s<d;s++)
      {	
	 gbase=gf+(r+s*c)*p*q*R;
	 fbase=ff+(r+s*c)*p*q*W;
	 cbase=cf+(r+s*c)*q*q*W*R;

	 for (nm=0;nm<q*W;nm++)
	 {
	    for (km=0;km<p;km++)
	    {
#ifdef HAVE_COMPLEX_H
	       fbase[km+nm*p]=0.0;
	       for (mm=0;mm<q*R;mm++)
	       {
		 fbase[km+nm*p]+=gbase[km+mm*p]*cbase[mm+nm*q*R];
	       }
	       /* Scale because of FFTWs normalization. */
	       fbase[km+nm*p]=fbase[km+nm*p]/d;
#else
	       fbase[km+nm*p][0]=0.0;
	       fbase[km+nm*p][1]=0.0;
	       for (mm=0;mm<q*R;mm++)
	       {
		 fbase[km+nm*p][0]+=gbase[km+mm*p][0]*cbase[mm+nm*q*R][0]-gbase[km+mm*p][1]*cbase[mm+nm*q*R][1];
		 fbase[km+nm*p][1]+=gbase[km+mm*p][0]*cbase[mm+nm*q*R][1]+gbase[km+mm*p][1]*cbase[mm+nm*q*R][0];
	       }
	       /* Scale because of FFTWs normalization. */
	       fbase[km+nm*p][0]=fbase[km+nm*p][0]/d;
	       fbase[km+nm*p][1]=fbase[km+nm*p][1]/d;
#endif
	    }		  
	 }	      	 
      }
   }

         


   /* ----------- compute inverse signal factorization ---------- */


   /* Do ifft to begin inverse signal factorization.*/
   fftw_execute(p_before);

   /* Leading dimensions of the 4dim array. */
   ld2=p*q*W;
   ld3=c*p*q*W;

   for (w=0;w<W;w++)
   {
      for (s=0;s<d;s++)
      {
	 for (l=0;l<q;l++)
	 {
	    for (k=0;k<p;k++)
	    {
	       /* Add L*M to make sure it is always positive */
	       domod = div(k*M+s*p*M+l*(c-h_m*M)+L*M, L);
	       
	       for (r=0;r<c;r++)
	       {		  
#ifdef HAVE_COMPLEX_H
		  f[r+domod.rem+L*w] = ff[k+(l+q*w)*p+r*ld2+s*ld3];
#else
		  f[r+domod.rem+L*w][0] = ff[k+(l+q*w)*p+r*ld2+s*ld3][0];
		  f[r+domod.rem+L*w][1] = ff[k+(l+q*w)*p+r*ld2+s*ld3][1];
#endif
	       }
	    }
	 }
      }
   }           

    /* -----------  Clean up ----------------- */   
   ltfat_free(ff);
   ltfat_free(cf);
   
}