add numerical recipes library

lib/nr/ansi/examples/xfour1.c

@@ -0,0 +1,98 @@
+
+/* 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