add numerical recipes library

lib/nr/ansi/examples/xcyclic.c

@@ -0,0 +1,54 @@
+
+/* Driver for routine cyclic */
+
+#include <stdio.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define N 20
+
+int main(void)
+{
+	float alpha,beta,d,*a,*b,*c,*r,*x,**aa;
+	int i,j,*indx;
+	long idum=(-23);
+
+	indx=ivector(1,N);
+	a=vector(1,N);
+	b=vector(1,N);
+	c=vector(1,N);
+	r=vector(1,N);
+	x=vector(1,N);
+	aa=matrix(1,N,1,N);
+	for (i=1;i<=N;i++)
+		for (j=1;j<=N;j++) aa[i][j]=0.0;
+	for (i=1;i<=N;i++) {
+		b[i]=ran2(&idum);
+		aa[i][i]=b[i];
+		r[i]=ran2(&idum);
+	}
+	for (i=1;i<N;i++) {
+		a[i+1]=ran2(&idum);
+		aa[i+1][i]=a[i+1];
+		c[i]=ran2(&idum);
+		aa[i][i+1]=c[i];
+	}
+	alpha=ran2(&idum);
+	aa[N][1]=alpha;
+	beta=ran2(&idum);
+	aa[1][N]=beta;
+	cyclic(a,b,c,alpha,beta,r,x,N);
+	ludcmp(aa,N,indx,&d);
+	lubksb(aa,N,indx,r);
+	for (i=1;i<=N;i++) printf("%4d  %12.6e\n",i,(x[i]-r[i])/(x[i]+r[i]));
+	free_matrix(aa,1,N,1,N);
+	free_vector(x,1,N);
+	free_vector(r,1,N);
+	free_vector(c,1,N);
+	free_vector(b,1,N);
+	free_vector(a,1,N);
+	free_ivector(indx,1,N);
+	return 0;
+}
+#undef NRANSI