add numerical recipes library

lib/nr/ansi/examples/xgcf.c

@@ -0,0 +1,42 @@
+
+/* Driver for routine gcf */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define MAXSTR 80
+
+int main(void)
+{
+	char txt[MAXSTR];
+	int i,nval;
+	float a,val,x,gammcf,gln;
+	FILE *fp;
+
+	if ((fp = fopen("fncval.dat","r")) == NULL)
+		nrerror("Data file fncval.dat not found\n");
+	fgets(txt,MAXSTR,fp);
+	while (strncmp(txt,"Incomplete Gamma Function",25)) {
+		fgets(txt,MAXSTR,fp);
+		if (feof(fp)) nrerror("Data not found in fncval.dat\n");
+	}
+	fscanf(fp,"%d %*s",&nval);
+	printf("\n%s\n",txt);
+	printf("%4s %11s %14s %13s %13s %8s\n","a","x",
+		"actual","gcf(a,x)","gammln(a)","gln");
+	for (i=1;i<=nval;i++) {
+		fscanf(fp,"%f %f %f",&a,&x,&val);
+		if (x >= (a+1.0)) {
+			gcf(&gammcf,a,x,&gln);
+			printf("%6.2f%13.6f%13.6f%13.6f%12.6f%13.6f\n",
+				a,x,(1.0-val),gammcf,gammln(a),gln);
+		}
+	}
+	fclose(fp);
+	return 0;
+}
+#undef NRANSI