Zfour1.cin

// zfour.cin is C++ implermentation of the routine required for compilation of examples with DCT.

void zfour1(z_type data[], unsigned long nn, int isign) { unsigned long n,mmax,m,j,istep,i; double wtemp,wr,wpr,wpi,wi,theta; z_type tempr,tempi; n=nn << 1; j=1; for(i=1;ii){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) define SWAP(a,b) tempr=(a);(a)=(b);(b)=tempr
 * 1) undef SWAP