add numerical recipes library

lib/nr/ansi/examples/xqsimp.c

@@ -0,0 +1,33 @@
+
+/* Driver for routine qsimp */
+
+#include <stdio.h>
+#include <math.h>
+#define NRANSI
+#include "nr.h"
+
+#define PIO2 1.5707963
+
+/* Test function */
+float func(float x)
+{
+	return x*x*(x*x-2.0)*sin(x);
+}
+
+/* Integral of test function */
+float fint(float x)
+{
+	return 4.0*x*(x*x-7.0)*sin(x)-(pow(x,4.0)-14.0*x*x+28.0)*cos(x);
+}
+
+int main(void)
+{
+	float a=0.0,b=PIO2,s;
+
+	printf("Integral of func computed with QSIMP\n\n");
+	printf("Actual value of integral is %12.6f\n",fint(b)-fint(a));
+	s=qsimp(func,a,b);
+	printf("Result from routine QSIMP is %11.6f\n",s);
+	return 0;
+}
+#undef NRANSI