EcgSynKit/test.org

Test

#define SWAP(a,b) tempr=(a);(a)=(b);(b)=tempr

void dfour1(double data[], unsigned long nn, int isign)
{
	unsigned long n,mmax,m,j,istep,i;
	double wtemp,wr,wpr,wpi,wi,theta;
	double tempr,tempi;

	n=nn << 1;
	j=1;
	for (i=1;i<n;i+=2) {
		if (j > 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;
	}
}
#undef SWAP

double d[] = {1.5, 2.5, -0.8, 1.2, 2.2, -1.0, -0.5, 0.4, 2.4, 3.1, 0.1, 3.8, 5.0, -0.1, 3.2, 2.1};
//double d[] = {1.0, 1.0, 1.0, 1.0, 0.0, 0.0, 0.0, 0.0};
//double d[] = {0.0, 0.0, 1.0, 0.0, 2.0, 0.0, 3.0, 0.0};

dfour1(d-1, 8, 1);


for (int i = 0; i <16; ++i) {
    printf("%f, ", d[i]);
}

printf("\n");

13.1

12.0

5.020458

-7.289087

-5.8

3.3

-0.73934

-0.416295

9.1

-3.0

-5.020458

0.489087

-0.8

10.1

-2.86066

4.816295