📄 dpfafft.c
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t26r = t21r-t22r; t26i = t21i-t22i; t27r = t9r+t24r; t27i = t9i+t24i; t28r = t10r+t23r; t28i = t10i+t23i; t29r = t9r-t24r; t29i = t9i-t24i; t30r = t10r-t23r; t30i = t10i-t23i; t31r = t5r+t17r; t31i = t5i+t17i; t32r = t11r+t25r; t32i = t11i+t25i; t33r = t3r+t18r; t33i = t3i+t18i; t34r = c2*t29r-c6*t30r; t34i = c2*t29i-c6*t30i; t35r = t3r-t18r; t35i = t3i-t18i; t36r = c7*t27r-c3*t28r; t36i = c7*t27i-c3*t28i; t37r = t4r+t19r; t37i = t4i+t19i; t38r = c3*t27r+c7*t28r; t38i = c3*t27i+c7*t28i; t39r = t4r-t19r; t39i = t4i-t19i; t40r = c6*t29r+c2*t30r; t40i = c6*t29i+c2*t30i; t41r = c4*(t12r-t26r); t41i = c4*(t12i-t26i); t42r = c5*(t12r+t26r); t42i = c5*(t12i+t26i); y1r = t33r+t34r; y1i = t33i+t34i; y2r = t6r+t41r; y2i = t6i+t41i; y3r = t35r+t40r; y3i = t35i+t40i; y4r = t5r-t17r; y4i = t5i-t17i; y5r = t35r-t40r; y5i = t35i-t40i; y6r = t6r-t41r; y6i = t6i-t41i; y7r = t33r-t34r; y7i = t33i-t34i; y9r = t38r-t37r; y9i = t38i-t37i; y10r = t42r-t20r; y10i = t42i-t20i; y11r = t36r+t39r; y11i = t36i+t39i; y12r = c1*(t11r-t25r); y12i = c1*(t11i-t25i); y13r = t36r-t39r; y13i = t36i-t39i; y14r = t42r+t20r; y14i = t42i+t20i; y15r = t38r+t37r; y15i = t38i+t37i; z[j00] = t31r+t32r; z[j00+1] = t31i+t32i; z[j01] = y1r-y15i; z[j01+1] = y1i+y15r; z[j2] = y2r-y14i; z[j2+1] = y2i+y14r; z[j3] = y3r-y13i; z[j3+1] = y3i+y13r; z[j4] = y4r-y12i; z[j4+1] = y4i+y12r; z[j5] = y5r-y11i; z[j5+1] = y5i+y11r; z[j6] = y6r-y10i; z[j6+1] = y6i+y10r; z[j7] = y7r-y9i; z[j7+1] = y7i+y9r; z[j8] = t31r-t32r; z[j8+1] = t31i-t32i; z[j9] = y7r+y9i; z[j9+1] = y7i-y9r; z[j10] = y6r+y10i; z[j10+1] = y6i-y10r; z[j11] = y5r+y11i; z[j11+1] = y5i-y11r; z[j12] = y4r+y12i; z[j12+1] = y4i-y12r; z[j13] = y3r+y13i; z[j13+1] = y3i-y13r; z[j14] = y2r+y14i; z[j14+1] = y2i-y14r; z[j15] = y1r+y15i; z[j15+1] = y1i-y15r; jt = j15+2; j15 = j14+2; j14 = j13+2; j13 = j12+2; j12 = j11+2; j11 = j10+2; j10 = j9+2; j9 = j8+2; j8 = j7+2; j7 = j6+2; j6 = j5+2; j5 = j4+2; j4 = j3+2; j3 = j2+2; j2 = j01+2; j01 = j00+2; j00 = jt; } continue; } }}void pfacr_d (int isign, int n, real_complex cz[], real rz[])/*****************************************************************************Prime factor fft: real_complex to real transform******************************************************************************Input:isign sign of isign is the sign of exponent in fourier kerneln length of transform (see notes below)cz array[n/2+1] of real_complex values (may be equivalenced to rz)Output:rz array[n] of real values (may be equivalenced to cz)******************************************************************************Notes:Because pfacr uses pfacc to do most of the work, n must be even and n/2 must be a valid length for pfacc. The simplest way toobtain a valid n is via n = npfar(nmin). A more optimal n can be obtained with npfaro.******************************************************************************References: Press et al, 1988, Numerical Recipes in C, p. 417.Also, see notes and references for function pfacc.******************************************************************************Author: Dave Hale, Colorado School of Mines, 06/13/89*****************************************************************************/{ int i,ir,ii,jr,ji,no2; real *z,tempr,tempi,sumr,sumi,difr,difi; double wr,wi,wpr,wpi,wtemp,theta; /* copy input to output and fix dc and nyquist */ z = (real*)cz; for (i=2; i<n; i++) rz[i] = z[i]; rz[1] = z[0]-z[n]; rz[0] = z[0]+z[n]; z = rz; /* initialize cosine-sine recurrence */ theta = 2.0*PI/(double)n; if (isign>0) theta = -theta; wtemp = sin(0.5*theta); wpr = -2.0*wtemp*wtemp; wpi = sin(theta); wr = 1.0+wpr; wi = wpi; /* twiddle */ no2 = n/2; for (ir=2,ii=3,jr=n-2,ji=n-1; ir<=no2; ir+=2,ii+=2,jr-=2,ji-=2) { sumr = z[ir]+z[jr]; sumi = z[ii]+z[ji]; difr = z[ir]-z[jr]; difi = z[ii]-z[ji]; tempr = wi*difr-wr*sumi; tempi = wi*sumi+wr*difr; z[ir] = sumr+tempr; z[ii] = difi+tempi; z[jr] = sumr-tempr; z[ji] = tempi-difi; wtemp = wr; wr += wr*wpr-wi*wpi; wi += wi*wpr+wtemp*wpi; } /* do real_complex to real_complex transform */ pfacc_d(isign,n/2,(real_complex*)z);}void pfarc_d (int isign, int n, real rz[], real_complex cz[])/*****************************************************************************Prime factor fft: real to real_complex transform******************************************************************************Input:isign sign of isign is the sign of exponent in fourier kerneln length of transform; must be even (see notes below)rz array[n] of real values (may be equivalenced to cz)Output:cz array[n/2+1] of real_complex values (may be equivalenced to rz)******************************************************************************Notes:Because pfarc uses pfacc to do most of the work, n must be even and n/2 must be a valid length for pfacc. The simplest way toobtain a valid n is via n = npfar(nmin). A more optimal n can be obtained with npfaro.******************************************************************************References: Press et al, 1988, Numerical Recipes in C, p. 417.Also, see notes and references for function pfacc.******************************************************************************Author: Dave Hale, Colorado School of Mines, 06/13/89*****************************************************************************/{ int i,ir,ii,jr,ji,no2; real *z,tempr,tempi,sumr,sumi,difr,difi; double wr,wi,wpr,wpi,wtemp,theta; /* copy input to output while scaling */ z = (real*)cz; for (i=0; i<n; i++) z[i] = 0.5*rz[i]; /* do real_complex to real_complex transform */ pfacc_d(isign,n/2,cz); /* fix dc and nyquist */ z[n] = 2.0*(z[0]-z[1]); z[0] = 2.0*(z[0]+z[1]); z[n+1] = 0.0; z[1] = 0.0; /* initialize cosine-sine recurrence */ theta = 2.0*PI/(double)n; if (isign<0) theta = -theta; wtemp = sin(0.5*theta); wpr = -2.0*wtemp*wtemp; wpi = sin(theta); wr = 1.0+wpr; wi = wpi; /* twiddle */ no2 = n/2; for (ir=2,ii=3,jr=n-2,ji=n-1; ir<=no2; ir+=2,ii+=2,jr-=2,ji-=2) { sumr = z[ir]+z[jr]; sumi = z[ii]+z[ji]; difr = z[ir]-z[jr]; difi = z[ii]-z[ji]; tempr = wi*difr+wr*sumi; tempi = wi*sumi-wr*difr; z[ir] = sumr+tempr; z[ii] = difi+tempi; z[jr] = sumr-tempr; z[ji] = tempi-difi; wtemp = wr; wr += wr*wpr-wi*wpi; wi += wi*wpr+wtemp*wpi; }}void pfamcc_d (int isign, int n, int nt, int k, int kt, real_complex cz[])/*****************************************************************************Prime factor fft: multiple real_complex to real_complex transforms, in place******************************************************************************Input:isign sign of isign is the sign of exponent in fourier kerneln number of real_complex elements per transform (see notes below)nt number of transformsk stride in real_complex elements within transformskt stride in real_complex elements between transformsz array of real_complex elements to be transformed in placeOutput:z array of real_complex elements transformed******************************************************************************Notes:n must be factorable into mutually prime factors taken from the set {2,3,4,5,7,8,9,11,13,16}. in other words, n = 2**p * 3**q * 5**r * 7**s * 11**t * 13**uwhere 0 <= p <= 4, 0 <= q <= 2, 0 <= r,s,t,u <= 1is required for pfamcc to yield meaningful results. thisrestriction implies that n is restricted to the range 1 <= n <= 720720 (= 5*7*9*11*13*16)To perform a two-dimensional transform of an n1 by n2 real_complex array (assuming that both n1 and n2 are valid "n"), stored with n1 fast and n2 slow: pfamcc(isign,n1,n2,1,n1,z); (to transform 1st dimension) pfamcc(isign,n2,n1,n1,1,z); (to transform 2nd dimension)******************************************************************************References: Temperton, C., 1985, Implementation of a self-sortingin-place prime factor fft algorithm: Journal ofComputational Physics, v. 58, p. 283-299.Temperton, C., 1988, A new set of minimum-add rotatedrotated dft modules: Journal of Computational Physics,v. 75, p. 190-198.******************************************************************************Author: Dave Hale, Colorado School of Mines, 06/15/89*****************************************************************************/{ static int kfax[] = { 16,13,11,9,8,7,5,4,3,2 }; register real *z=(real*)cz; register int j00,j01,j2,j3,j4,j5,j6,j7,j8,j9,j10,j11,j12,j13,j14,j15; int nleft,jfax,ifac,jfac,iinc,imax,ndiv,m,mm=0,mu=0,l,istep,jstep, jt,i0,i1,i2,i3,i4,i5,i6,i7,i8,i9,i10,i11,i12,i13,i14,i15,it; real t1r,t1i,t2r,t2i,t3r,t3i,t4r,t4i,t5r,t5i, t6r,t6i,t7r,t7i,t8r,t8i,t9r,t9i,t10r,t10i, t11r,t11i,t12r,t12i,t13r,t13i,t14r,t14i,t15r,t15i, t16r,t16i,t17r,t17i,t18r,t18i,t19r,t19i,t20r,t20i, t21r,t21i,t22r,t22i,t23r,t23i,t24r,t24i,t25r,t25i, t26r,t26i,t27r,t27i,t28r,t28i,t29r,t29i,t30r,t30i, t31r,t31i,t32r,t32i,t33r,t33i,t34r,t34i,t35r,t35i, t36r,t36i,t37r,t37i,t38r,t38i,t39r,t39i,t40r,t40i, t41r,t41i,t42r,t42i, y1r,y1i,y2r,y2i,y3r,y3i,y4r,y4i,y5r,y5i, y6r,y6i,y7r,y7i,y8r,y8i,y9r,y9i,y10r,y10i, y11r,y11i,y12r,y12i,y13r,y13i,y14r,y14i,y15r,y15i, c1,c2,c3,c4,c5,c6,c7,c8,c9,c10,c11,c12; /* determine step within and between transforms */ istep = 2*k; jstep = 2*kt; /* keep track of n left after dividing by factors */ nleft = n; /* begin loop over possible factors (from biggest to smallest) */ for (jfax=0; jfax<NFAX; jfax++) { /* skip if not a mutually prime factor of n */ ifac = kfax[jfax]; ndiv = nleft/ifac; if (ndiv*ifac!=nleft) continue; /* update n left and determine n divided by factor */ nleft = ndiv; m = n/ifac; /* determine rotation factor mu and stride mm */ for (jfac=1; jfac<=ifac; jfac++) { mu = jfac; mm = jfac*m; if (mm%ifac==1) break; } /* adjust rotation factor for sign of transform */ if (isign<0) mu = ifac-mu; /* compute stride, limit, and pointers */ iinc = istep*mm; imax = istep*n; i0 = 0; i1 = i0+iinc; /* if factor is 2 */ if (ifac==2) { for (l=0; l<m; l++) { j00 = i0; j01 = i1; for (jt=0; jt<nt; jt++) { t1r = z[j00]-z[j01]; t1i = z[j00+1]-z[j01+1]; z[j00] = z[j00]+z[j01]; z[j00+1] = z[j00+1]+z[j01+1]; z[j01] = t1r; z[j01+1] = t1i; j00 += jstep; j01 += jstep; } it = i1+istep; i1 = i0+istep; i0 = it; } continue; } i2 = i1+iinc; if (i2>=imax) i2 = i2-imax; /* if factor is 3 */ if (ifac==3) { if (mu==1) c1 = P866; else c1 = -P866; for (l=0; l<m; l++) { j00 = i0; j01 = i1; j2 = i2; for (jt=0; jt<nt; jt++) { t1r = z[j01]+z[j2]; t1i = z[j01+1]+z[j2+1]; y1r = z[j00]-0.5*t1r; y1i = z[j00+1]-0.5*t1i; y2r = c1*(z[j01]-z[j2]); y2i = c1*(z[j01+1]-z[j2+1]); z[j00] = z[j00]+t1r; z[j00+1] = z[j00+1]+t1i; z[j01] = y1r-y2i; z[j01+1] = y1i+y2r; z[j2] = y1r+y2i; z[j2+1] = y1i-y2r; j00 += jstep; j01 += jstep; j2 += jstep; } it = i2+istep; i2 = i1+istep; i1 = i0+istep; i0 = it; } continue; } i3 = i2+iinc; if (i3>=imax) i3 = i3-imax; /* if factor is 4 */ if (ifac==4) { if (mu==1) c1 = 1.0; else c1 = -1.0; for (l=0; l<m; l++) { j00 = i0; j01 = i1; j2 = i2; j3 = i3; for (jt=0; jt<nt; jt++) { t1r = z[j00]+z[j2]; t1i = z[j00+1]+z[j2+1]; t2r = z[j01]+z[j3]; t2i = z[j01+1]+z[j3+1]; y1r = z[j00]-z[j2]; y1i = z[j00+1]-z[j2+1]; y3r = c1*(z[j01]-z[j3]); y3i = c1*(z[j01+1]-z[j3+1]); z[j00] = t1r+t2r; z[j00+1] = t1i+t2i; z[j01] = y1r-y3i; z[j01+1] = y1i+y3r; z[j2] = t1r-t2r; z[j2+1] = t1i-t2i; z[j3] = y1r+y3i; z[j3+1] = y1i-y3r; j00 += jstep; j01 += jstep; j2 += jstep; j3 += jstep; } it = i3+istep; i3 = i2+istep; i2 = i1+istep; i1 = i0+istep; i0 = it; } continue; } i4 = i3+iinc; if (i4>=imax) i4 = i4-imax; /* if factor is 5 */
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