add numerical recipes library

lib/nr/ansi/recipes/slvsml.c

@@ -0,0 +1,9 @@
+
+void slvsml(double **u, double **rhs)
+{
+	void fill0(double **u, int n);
+	double h=0.5;
+
+	fill0(u,3);
+	u[2][2] = -h*h*rhs[2][2]/4.0;
+}