add numerical recipes library

lib/nr/ansi/examples/xqgaus.c

@@ -0,0 +1,33 @@
+
+/* Driver for routine qgaus */
+
+#include <stdio.h>
+#include <math.h>
+#define NRANSI
+#include "nr.h"
+
+#define X1 0.0
+#define X2 5.0
+#define NVAL 10
+
+float func(float x)
+{
+	return x*exp(-x);
+}
+
+int main(void)
+{
+	float dx,ss,x;
+	int i;
+
+	dx=(X2-X1)/NVAL;
+	printf("\n%s %10s %13s\n\n","0.0 to","qgaus","expected");
+	for (i=1;i<=NVAL;i++) {
+		x=X1+i*dx;
+		ss=qgaus(func,X1,x);
+		printf("%5.2f %12.6f %12.6f\n",x,ss,
+			(-(1.0+x)*exp(-x)+(1.0+X1)*exp(-X1)));
+	}
+	return 0;
+}
+#undef NRANSI