add numerical recipes library

lib/nr/ansi/examples/xchstwo.c

@@ -0,0 +1,43 @@
+
+/* Driver for routine chstwo */
+
+#include <stdio.h>
+#include <math.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define NBINS 10
+#define NPTS 2000
+
+int main(void)
+{
+	long idum=(-17);
+	int i,ibin,j;
+	float chsq,df,prob,x,*bins1,*bins2;
+
+	bins1=vector(1,NBINS);
+	bins2=vector(1,NBINS);
+	for (j=1;j<=NBINS;j++) {
+		bins1[j]=0.0;
+		bins2[j]=0.0;
+	}
+	for (i=1;i<=NPTS;i++) {
+		x=expdev(&idum);
+		ibin=(int) (x*NBINS/3.0+1);
+		if (ibin <= NBINS) ++bins1[ibin];
+		x=expdev(&idum);
+		ibin=(int) (x*NBINS/3.0+1);
+		if (ibin <= NBINS) ++bins2[ibin];
+	}
+	chstwo(bins1,bins2,NBINS,0,&df,&chsq,&prob);
+	printf("\n%15s %15s\n","dataset 1","dataset 2");
+	for (i=1;i<=NBINS;i++)
+		printf("%13.2f %15.2f\n",bins1[i],bins2[i]);
+	printf("\n%18s %12.4f\n","chi-squared:",chsq);
+	printf("%18s %12.4f\n","probability:",prob);
+	free_vector(bins2,1,NBINS);
+	free_vector(bins1,1,NBINS);
+	return 0;
+}
+#undef NRANSI