add numerical recipes library

lib/nr/k_and_r/recipes/qtrap.c

@@ -0,0 +1,25 @@
+
+#include <math.h>
+#define EPS 1.0e-5
+#define JMAX 20
+
+float qtrap(func,a,b)
+float (*func)(),a,b;
+{
+	float trapzd();
+	void nrerror();
+	int j;
+	float s,olds=0.0;
+
+	for (j=1;j<=JMAX;j++) {
+		s=trapzd(func,a,b,j);
+		if (j > 5)
+			if (fabs(s-olds) < EPS*fabs(olds) ||
+				(s == 0.0 && olds == 0.0)) return s;
+		olds=s;
+	}
+	nrerror("Too many steps in routine qtrap");
+	return 0.0;
+}
+#undef EPS
+#undef JMAX