add numerical recipes library

lib/nr/ansi/recipes/chebev.c

@@ -0,0 +1,16 @@
+
+float chebev(float a, float b, float c[], int m, float x)
+{
+	void nrerror(char error_text[]);
+	float d=0.0,dd=0.0,sv,y,y2;
+	int j;
+
+	if ((x-a)*(x-b) > 0.0) nrerror("x not in range in routine chebev");
+	y2=2.0*(y=(2.0*x-a-b)/(b-a));
+	for (j=m-1;j>=1;j--) {
+		sv=d;
+		d=y2*d-dd+c[j];
+		dd=sv;
+	}
+	return y*d-dd+0.5*c[0];
+}