add numerical recipes library

lib/nr/k_and_r/recipes/gaucof.c

@@ -0,0 +1,25 @@
+
+#include <math.h>
+#include "nrutil.h"
+
+void gaucof(n,a,b,amu0,x,w)
+float a[],amu0,b[],w[],x[];
+int n;
+{
+	void eigsrt(),tqli();
+	int i,j;
+	float **z;
+
+	z=matrix(1,n,1,n);
+	for (i=1;i<=n;i++) {
+		if (i != 1) b[i]=sqrt(b[i]);
+		for (j=1;j<=n;j++) z[i][j]=(float)(i == j);
+	}
+	tqli(a,b,n,z);
+	eigsrt(a,z,n);
+	for (i=1;i<=n;i++) {
+		x[i]=a[i];
+		w[i]=amu0*z[1][i]*z[1][i];
+	}
+	free_matrix(z,1,n,1,n);
+}