/* Driver for routine four1 */#include <stdio.h>#include <math.h>#define NRANSI#include "nr.h"#include "nrutil.h"void prntft(float data[],unsigned long nn){	unsigned long n;	printf("%4s %13s %13s %12s %13s\n",		"n","real(n)","imag.(n)","real(N-n)","imag.(N-n)");	printf("   0 %14.6f %12.6f %12.6f %12.6f\n",		data[1],data[2],data[1],data[2]);	for (n=3;n<=nn+1;n+=2) {		printf("%4lu %14.6f %12.6f %12.6f %12.6f\n",			((n-1)/2),data[n],data[n+1],			data[2*nn+2-n],data[2*nn+3-n]);	}	printf(" press return to continue ...\n");	(void) getchar();	return;}#define NN 32#define NN2 (2*NN)int main(void){	long i;	int isign;	float *data,*dcmp;	data=vector(1,NN2);	dcmp=vector(1,NN2);	printf("h(t)=real-valued even-function\n");	printf("h(n)=h(N-n) and real?\n");	for (i=1;i<NN2;i+=2) {		data[i]=1.0/(SQR((float) (i-NN-1)/NN)+1.0);		data[i+1]=0.0;	}	isign=1;	four1(data,NN,isign);	prntft(data,NN);	printf("h(t)=imaginary-valued even-function\n");	printf("h(n)=h(N-n) and imaginary?\n");	for (i=1;i<NN2;i+=2) {		data[i+1]=1.0/(SQR((float) (i-NN-1)/NN)+1.0);		data[i]=0.0;	}	isign=1;	four1(data,NN,isign);	prntft(data,NN);	printf("h(t)=real-valued odd-function\n");	printf("h(n) = -h(N-n) and imaginary?\n");	for (i=1;i<NN2;i+=2) {		data[i]=((float) (i-NN-1)/NN)/(SQR((float) (i-NN-1)/NN)+1.0);		data[i+1]=0.0;	}	data[1]=0.0;	isign=1;	four1(data,NN,isign);	prntft(data,NN);	printf("h(t)=imaginary-valued odd-function\n");	printf("h(n) = -h(N-n) and real?\n");	for (i=1;i<NN2;i+=2) {		data[i+1]=((float) (i-NN-1)/NN)/(SQR((float) (i-NN-1)/NN)+1.0);		data[i]=0.0;	}	data[2]=0.0;	isign=1;	four1(data,NN,isign);	prntft(data,NN);	/* transform, inverse-transform test */	for (i=1;i<NN2;i+=2) {		data[i]=1.0/(SQR(0.5*(i-NN-1.0)/NN)+1.0);		dcmp[i]=data[i];		data[i+1]=(0.25*(i-NN-1.0)/NN)*exp(-SQR(0.5*(i-NN-1)/NN));		dcmp[i+1]=data[i+1];	}	isign=1;	four1(data,NN,isign);	isign = -1;	four1(data,NN,isign);	printf("%23s %33s \n","original data:","double fourier transform:");	printf("\n %3s %15s %12s %12s %12s \n",		"k","real h(k)","imag h(k)","real h(k)","imag h(k)");	for (i=1;i<NN;i+=2)		printf("%4lu %14.6f %12.6f %12.6f %12.6f\n",			(i+1)/2,dcmp[i],dcmp[i+1],data[i]/NN,data[i+1]/NN);	free_vector(dcmp,1,NN2);	free_vector(data,1,NN2);	return 0;}#undef NRANSI