add numerical recipes library

lib/nr/ansi/examples/xsplin2.c

@@ -0,0 +1,46 @@
+
+/* Driver for routine splin2 */
+
+#include <stdio.h>
+#include <math.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define M 10
+#define N 10
+
+int main(void)
+{
+	int i,j;
+	float f,ff,x1x2,xx1,xx2,*x1,*x2,**y,**y2;
+
+	x1=vector(1,N);
+	x2=vector(1,N);
+	y=matrix(1,M,1,N);
+	y2=matrix(1,M,1,N);
+	for (i=1;i<=M;i++) x1[i]=0.2*i;
+	for (i=1;i<=N;i++) x2[i]=0.2*i;
+	for (i=1;i<=M;i++) {
+		for (j=1;j<=N;j++) {
+			x1x2=x1[i]*x2[j];
+			y[i][j]=x1x2*exp(-x1x2);
+		}
+	}
+	splie2(x1,x2,y,M,N,y2);
+	printf("%9s %12s %14s %12s\n","x1","x2","splin2","actual");
+	for (i=1;i<=10;i++) {
+		xx1=0.1*i;
+		xx2=xx1*xx1;
+		splin2(x1,x2,y,y2,M,N,xx1,xx2,&f);
+		x1x2=xx1*xx2;
+		ff=x1x2*exp(-x1x2);
+		printf("%12.6f %12.6f %12.6f %12.6f\n",xx1,xx2,f,ff);
+	}
+	free_matrix(y2,1,M,1,N);
+	free_matrix(y,1,M,1,N);
+	free_vector(x2,1,N);
+	free_vector(x1,1,N);
+	return 0;
+}
+#undef NRANSI