add numerical recipes library

lib/nr/ansi/examples/xpolin2.c

@@ -0,0 +1,48 @@
+
+/* Driver for routine polin2 */
+
+#include <stdio.h>
+#include <math.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define N 5
+#define PI 3.1415926
+
+int main(void)
+{
+	int i,j;
+	float dy,f,x1,x2,y,*x1a,*x2a,**ya;
+
+	x1a=vector(1,N);
+	x2a=vector(1,N);
+	ya=matrix(1,N,1,N);
+	for (i=1;i<=N;i++) {
+		x1a[i]=i*PI/N;
+		for (j=1;j<=N;j++) {
+			x2a[j]=1.0*j/N;
+			ya[i][j]=sin(x1a[i])*exp(x2a[j]);
+		}
+	}
+	/* test 2-dimensional interpolation */
+	printf("\nTwo dimensional interpolation of sin(x1)exp(x2)\n");
+	printf("%9s %12s %13s %16s %11s\n",
+		"x1","x2","f(x)","interpolated","error");
+	for (i=1;i<=4;i++) {
+		x1=(-0.1+i/5.0)*PI;
+		for (j=1;j<=4;j++) {
+			x2 = -0.1+j/5.0;
+			f=sin(x1)*exp(x2);
+			polin2(x1a,x2a,ya,N,N,x1,x2,&y,&dy);
+			printf("%12.6f %12.6f %12.6f %12.6f %15.6f\n",
+				x1,x2,f,y,dy);
+		}
+		printf ("***********************************\n");
+	}
+	free_matrix(ya,1,N,1,N);
+	free_vector(x2a,1,N);
+	free_vector(x1a,1,N);
+	return 0;
+}
+#undef NRANSI