Four1.cin

// I have converted the zsinft.cin from complex double to float. The result is below. it should be close to the original by the "numerical recipes", but I cannot access the original to check this.

//The routine below is float implementation of the sin fourier transform (FSFT. It is supposed to be compiled together with four1.cin and realft.cin
 * 1) define SWAP(a,b) tempr=(a);(a)=(b);(b)=tempr

void four1(float data[], unsigned long nn, int isign) {       unsigned long n,mmax,m,j,istep,i; float wtemp,wr,wpr,wpi,wi,theta; //double float tempr,tempi; // ztype

n=nn << 1; j=1; for (i=1;i i) { SWAP(data[j],data[i]); SWAP(data[j+1],data[i+1]); }               m=n >> 1; while (m >= 2 && j > m) { j -= m;                       m >>= 1; }               j += m;        } mmax=2; while (n > mmax) { istep=mmax << 1; theta=isign*(6.28318530717959/mmax); wtemp=sin(0.5*theta); wpr = -2.0*wtemp*wtemp; wpi=sin(theta); wr=1.0; wi=0.0; for (m=1;m<mmax;m+=2) { for (i=m;i<=n;i+=istep) { j=i+mmax; tempr=wr*data[j]-wi*data[j+1]; tempi=wr*data[j+1]+wi*data[j]; data[j]=data[i]-tempr; data[j+1]=data[i+1]-tempi; data[i] += tempr; data[i+1] += tempi; }                       wr=(wtemp=wr)*wpr-wi*wpi+wr; wi=wi*wpr+wtemp*wpi+wi; }               mmax=istep; } }
 * 1) undef SWAP