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2025-02-Numerical/lib/nr/k_and_r/recipes/zroots.c
2025-09-12 18:55:25 +09:00

42 lines
693 B
C

#include <math.h>
#include "complex.h"
#define EPS 2.0e-6
#define MAXM 100
void zroots(a,m,roots,polish)
fcomplex a[],roots[];
int m,polish;
{
void laguer();
int i,its,j,jj;
fcomplex x,b,c,ad[MAXM];
for (j=0;j<=m;j++) ad[j]=a[j];
for (j=m;j>=1;j--) {
x=Complex(0.0,0.0);
laguer(ad,j,&x,&its);
if (fabs(x.i) <= 2.0*EPS*fabs(x.r)) x.i=0.0;
roots[j]=x;
b=ad[j];
for (jj=j-1;jj>=0;jj--) {
c=ad[jj];
ad[jj]=b;
b=Cadd(Cmul(x,b),c);
}
}
if (polish)
for (j=1;j<=m;j++)
laguer(a,m,&roots[j],&its);
for (j=2;j<=m;j++) {
x=roots[j];
for (i=j-1;i>=1;i--) {
if (roots[i].r <= x.r) break;
roots[i+1]=roots[i];
}
roots[i+1]=x;
}
}
#undef EPS
#undef MAXM