add numerical recipes library

lib/nr/ansi/examples/xmnbrak.c

@@ -0,0 +1,28 @@
+
+/* Driver for routine mnbrak */
+
+#include <stdio.h>
+#define NRANSI
+#include "nr.h"
+
+float func(float x)
+{
+	return bessj0(x);
+}
+
+int main(void)
+{
+	float ax,bx,cx,fa,fb,fc;
+	int i;
+
+	for (i=1;i<=10;i++) {
+		ax=i*0.5;
+		bx=(i+1.0)*0.5;
+		mnbrak(&ax,&bx,&cx,&fa,&fb,&fc,func);
+		printf("%14s %12s %12s\n","a","b","c");
+		printf("%3s %14.6f %12.6f %12.6f\n","x",ax,bx,cx);
+		printf("%3s %14.6f %12.6f %12.6f\n","f",fa,fb,fc);
+	}
+	return 0;
+}
+#undef NRANSI