add numerical recipes library

lib/nr/ansi/examples/xhunt.c

@@ -0,0 +1,45 @@
+
+/* Driver for routine hunt */
+
+#include <stdio.h>
+#include <math.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define N 100
+
+int main(void)
+{
+	unsigned long i,j,ji;
+	float x,*xx;
+
+	xx=vector(1,N);
+	/* create array to be searched */
+	for (i=1;i<=N;i++)
+		xx[i]=exp(i/20.0)-74.0;
+	printf("\n  result of:   j=0 indicates x too small\n");
+	printf("%14s j=100 indicates x too large"," ");
+	printf("\n%12s %8s %4s %11s %13s \n",
+		"locate:","guess","j","xx(j)","xx(j+1)");
+	/* do test */
+	for (i=1;i<=19;i++) {
+		x = -100.0+10.0*i;
+		/* trial parameter */
+		j=(ji=5*i);
+		/* begin search */
+		hunt(xx,N,x,&j);
+		if ((j < N) && (j > 0))
+			printf("%12.5f %6lu %6lu %12.6f %12.6f \n",
+				x,ji,j,xx[j],xx[j+1]);
+		else if (j == N)
+			printf("%12.5f %6lu %6lu %12.6f %s \n",
+				x,ji,j,xx[j],"   upper lim");
+		else
+			printf("%12.5f %6lu %6lu %s %12.6f \n",
+				x,ji,j,"   lower lim",xx[j+1]);
+	}
+	free_vector(xx,1,N);
+	return 0;
+}
+#undef NRANSI