add numerical recipes library

lib/nr/ansi/recipes/fred2.c

@@ -0,0 +1,27 @@
+
+#define NRANSI
+#include "nrutil.h"
+
+void fred2(int n, float a, float b, float t[], float f[], float w[],
+	float (*g)(float), float (*ak)(float, float))
+{
+	void gauleg(float x1, float x2, float x[], float w[], int n);
+	void lubksb(float **a, int n, int *indx, float b[]);
+	void ludcmp(float **a, int n, int *indx, float *d);
+	int i,j,*indx;
+	float d,**omk;
+
+	indx=ivector(1,n);
+	omk=matrix(1,n,1,n);
+	gauleg(a,b,t,w,n);
+	for (i=1;i<=n;i++) {
+		for (j=1;j<=n;j++)
+			omk[i][j]=(float)(i == j)-(*ak)(t[i],t[j])*w[j];
+		f[i]=(*g)(t[i]);
+	}
+	ludcmp(omk,n,indx,&d);
+	lubksb(omk,n,indx,f);
+	free_matrix(omk,1,n,1,n);
+	free_ivector(indx,1,n);
+}
+#undef NRANSI