add numerical recipes library

lib/nr/ansi/examples/xerffc.c

@@ -0,0 +1,38 @@
+
+/* Driver for routine erffc */
+
+#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 x,val;
+	FILE *fp;
+
+	if ((fp = fopen("fncval.dat","r")) == NULL)
+		nrerror("Data file fncval.dat not found\n");
+	fgets(txt,MAXSTR,fp);
+	while (strncmp(txt,"Error Function",14)) {
+		fgets(txt,MAXSTR,fp);
+		if (feof(fp)) nrerror("Data not found in fncval.dat\n");
+	}
+	fscanf(fp,"%d %*s",&nval);
+	printf("\ncomplementary error function\n");
+	printf("%5s %12s %13s\n","x","actual","erfc(x)");
+	for (i=1;i<=nval;i++) {
+		fscanf(fp,"%f %f",&x,&val);
+		val=1.0-val;
+		printf("%6.2f %12.7f %12.7f\n",x,val,erffc(x));
+	}
+	fclose(fp);
+	return 0;
+}
+#undef NRANSI