add numerical recipes library

lib/nr/ansi/examples/xbessik.c

@@ -0,0 +1,40 @@
+
+/* Driver for routine bessik */
+
+#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 ri,rk,rip,rkp,x,xnu,xri,xrk,xrip,xrkp;
+	FILE *fp;
+
+	if ((fp = fopen("fncval.dat","r")) == NULL)
+		nrerror("Data file fncval.dat not found\n");
+	fgets(txt,MAXSTR,fp);
+	while (strncmp(txt,"Modified Bessel Functions",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("%5s %7s\n%14s %16s %17s %16s\n%14s %16s %17s %16s\n",
+		"xnu","x","ri","rk","rip","rkp","xri","xrk","xrip","xrkp");
+	for (i=1;i<=nval;i++) {
+		fscanf(fp,"%f %f %f %f %f %f",&xnu,&x,&ri,&rk,&rip,&rkp);
+		bessik(x,xnu,&xri,&xrk,&xrip,&xrkp);
+		printf("%5.2f %5.2f\n\t%16.6e %16.6e %16.6e %16.6e\n",xnu,x,ri,rk,rip,rkp);
+		printf("\t%16.6e %16.6e %16.6e %16.6e\n",xri,xrk,xrip,xrkp);
+	}
+	fclose(fp);
+	return 0;
+}
+#undef NRANSI