add numerical recipes library

lib/nr/ansi/examples/xfrprmn.c

@@ -0,0 +1,51 @@
+
+/* Driver for routine frprmn */
+
+#include <stdio.h>
+#include <math.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define NDIM 3
+#define FTOL 1.0e-6
+#define PIO2 1.5707963
+
+float func(float x[])
+{
+	return 1.0-bessj0(x[1]-0.5)*bessj0(x[2]-0.5)*bessj0(x[3]-0.5);
+}
+
+void dfunc(float x[],float df[])
+{
+	df[1]=bessj1(x[1]-0.5)*bessj0(x[2]-0.5)*bessj0(x[3]-0.5);
+	df[2]=bessj0(x[1]-0.5)*bessj1(x[2]-0.5)*bessj0(x[3]-0.5);
+	df[3]=bessj0(x[1]-0.5)*bessj0(x[2]-0.5)*bessj1(x[3]-0.5);
+}
+
+int main(void)
+{
+	int iter,k;
+	float angl,fret,*p;
+
+	p=vector(1,NDIM);
+	printf("Program finds the minimum of a function\n");
+	printf("with different trial starting vectors.\n");
+	printf("True minimum is (0.5,0.5,0.5)\n");
+	for (k=0;k<=4;k++) {
+		angl=PIO2*k/4.0;
+		p[1]=2.0*cos(angl);
+		p[2]=2.0*sin(angl);
+		p[3]=0.0;
+		printf("\nStarting vector: (%6.4f,%6.4f,%6.4f)\n",
+			p[1],p[2],p[3]);
+		frprmn(p,NDIM,FTOL,&iter,&fret,func,dfunc);
+		printf("Iterations: %3d\n",iter);
+		printf("Solution vector: (%6.4f,%6.4f,%6.4f)\n",
+			p[1],p[2],p[3]);
+		printf("Func. value at solution %14f\n",fret);
+	}
+	free_vector(p,1,NDIM);
+	return 0;
+}
+#undef NRANSI