#include <math.h>void sinft(float y[], int n){	void realft(float data[], unsigned long n, int isign);	int j,n2=n+2;	float sum,y1,y2;	double theta,wi=0.0,wr=1.0,wpi,wpr,wtemp;	theta=3.14159265358979/(double) n;	wtemp=sin(0.5*theta);	wpr = -2.0*wtemp*wtemp;	wpi=sin(theta);	y[1]=0.0;	for (j=2;j<=(n>>1)+1;j++) {		wr=(wtemp=wr)*wpr-wi*wpi+wr;		wi=wi*wpr+wtemp*wpi+wi;		y1=wi*(y[j]+y[n2-j]);		y2=0.5*(y[j]-y[n2-j]);		y[j]=y1+y2;		y[n2-j]=y1-y2;	}	realft(y,n,1);	y[1]*=0.5;	sum=y[2]=0.0;	for (j=1;j<=n-1;j+=2) {		sum += y[j];		y[j]=y[j+1];		y[j+1]=sum;	}}