add numerical recipes library

lib/nr/ansi/examples/xqroot.c

@@ -0,0 +1,49 @@
+
+/* Driver for routine qroot */
+
+#include <stdio.h>
+#include <math.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define N 6 /* degree of polynomial */
+#define EPS 1.0e-6
+#define NTRY 10
+#define TINY 1.0e-5
+
+int main(void)
+{
+	int i,j,nflag,nroot=0;
+	static float p[N+1]={10.0,-18.0,25.0,-24.0,16.0,-6.0,1.0};
+	float *b,*c;
+
+	b=vector(1,NTRY);
+	c=vector(1,NTRY);
+	printf("\nP(x)=x^6-6x^5+16x^4-24x^3+25x^2-18x+10\n");
+	printf("Quadratic factors x^2+bx+c\n\n");
+	printf("%6s %10s %12s \n\n","factor","b","c");
+	for (i=1;i<=NTRY;i++) {
+		c[i]=0.5*i;
+		b[i] = -0.5*i;
+		qroot(p,N,&b[i],&c[i],EPS);
+		if (nroot == 0) {
+			printf("%4d %15.6f %12.6f\n",nroot,b[i],c[i]);
+			nroot=1;
+		} else {
+			nflag=0;
+			for (j=1;j<=nroot;j++)
+				if ((fabs(b[i]-b[j]) < TINY)
+					&& (fabs(c[i]-c[j]) < TINY))
+					nflag=1;
+			if (nflag == 0) {
+				printf("%4d %15.6f %12.6f\n",nroot,b[i],c[i]);
+				++nroot;
+			}
+		}
+	}
+	free_vector(c,1,NTRY);
+	free_vector(b,1,NTRY);
+	return 0;
+}
+#undef NRANSI