add numerical recipes library

lib/nr/ansi/examples/xpolcoe.c

@@ -0,0 +1,63 @@
+
+/* Driver for routine polcoe */
+
+#include <stdio.h>
+#include <math.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define NP 4
+#define PI 3.1415926
+
+int main(void)
+{
+	int i,j,nfunc;
+	float f,sum,x,*coeff,*xa,*ya;
+
+	coeff=vector(0,NP);
+	xa=vector(0,NP);
+	ya=vector(0,NP);
+	for (nfunc=1;nfunc<=2;nfunc++) {
+		if (nfunc == 1) {
+			printf("sine function from 0 to PI\n\n");
+			for (i=0;i<=NP;i++) {
+				xa[i]=(i+1)*PI/(NP+1);
+				ya[i]=sin(xa[i]);
+			}
+		} else if (nfunc == 2) {
+			printf("exponential function from 0 to 1\n\n");
+			for (i=0;i<=NP;i++) {
+				xa[i]=1.0*(i+1)/(NP+1);
+				ya[i]=exp(xa[i]);
+			}
+		} else {
+			break;
+		}
+		polcoe(xa,ya,NP,coeff);
+		printf("  coefficients\n");
+		for (i=0;i<=NP;i++) printf("%12.6f",coeff[i]);
+		printf("\n\n%9s %13s %15s\n","x","f(x)","polynomial");
+		for (i=1;i<=10;i++) {
+			if (nfunc == 1) {
+				x=(-0.05+i/10.0)*PI;
+				f=sin(x);
+			} else if (nfunc == 2) {
+				x = -0.05+i/10.0;
+				f=exp(x);
+			}
+			sum=coeff[NP];
+			for (j=NP-1;j>=0;j--)
+				sum=coeff[j]+sum*x;
+			printf("%12.6f %12.6f %12.6f\n",x,f,sum);
+		}
+		printf("\n************************************\n");
+		printf("press RETURN\n");
+		(void) getchar();
+	}
+	free_vector(ya,0,NP);
+	free_vector(xa,0,NP);
+	free_vector(coeff,0,NP);
+	return 0;
+}
+#undef NRANSI