add numerical recipes library

lib/nr/ansi/examples/xwt1.c

@@ -0,0 +1,54 @@
+
+/* Driver for routine wt1 */
+#include <stdio.h>
+#include <math.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define NMAX 512
+#define NCEN 333
+#define NWID 33
+
+int main(void)
+{
+	unsigned long i,nused;
+	int itest,k;
+	float *u,*v,*w,frac,thresh,tmp;
+
+	u=vector(1,NMAX);
+	v=vector(1,NMAX);
+	w=vector(1,NMAX);
+	for (;;) {
+		printf("Enter k (4, -4, 12, or 20) and frac (0.0 to 1.0):\n");
+		if (scanf("%d %f",&k,&frac) == EOF) break;
+		frac=FMIN(1.0,FMAX(0.0,frac));
+		itest=(k == -4 ? 1 : 0);
+		if (k < 0) k = -k;
+		if (k != 4 && k != 12 && k != 20) continue;
+		for (i=1;i<=NMAX;i++)
+			w[i]=v[i]=(i > NCEN-NWID && i < NCEN+NWID ?
+				((float)(i-NCEN+NWID)*(float)(NCEN+NWID-i))/(NWID*NWID) : 0.0);
+		if (!itest) pwtset(k);
+		wt1(v,NMAX,1,itest ? daub4 : pwt);
+		for (i=1;i<=NMAX;i++) u[i]=fabs(v[i]);
+		thresh=select((int)((1.0-frac)*NMAX),NMAX,u);
+		nused=0;
+		for (i=1;i<=NMAX;i++) {
+			if (fabs(v[i]) <= thresh)
+				v[i]=0.0;
+			else
+				nused++;
+		}
+		wt1(v,NMAX,-1,itest ? daub4 : pwt);
+		for (thresh=0.0,i=1;i<=NMAX;i++)
+			if ((tmp=fabs(v[i]-w[i])) > thresh) thresh=tmp;
+		printf("k,NMAX,nused= %d %d %d\n",k,NMAX,nused);
+		printf("discrepancy= %12.6f\n",thresh);
+	}
+	free_vector(w,1,NMAX);
+	free_vector(v,1,NMAX);
+	free_vector(u,1,NMAX);
+	return 0;
+}
+#undef NRANSI