Re: NEC-LIST: routine for finding complex roots wanted

Riccardo Leone asked:

> Does anybody know, please, where may I find a fortran (or C) routine
> for complex roots seeking, numerically, of a generic complex function?
> (that is a MoM matrix determinant) Websites, or books...

Since the polynomial coefficients are complex, the roots will
generally not appear in conjugate pairs.

I have used a subroutine, PRTC, from the ancient IBM Scientific
Subroutine Library to determine all roots of such complex polynomials.
This routine is written in PL/I (which REALLY dates me).

Two readily available Fortran routines are CPQR79.F written by W. H.
Vandevender of SNLA, and CPZERO.F written by D. K. Kahaner of NIST.
These are part of the SLATEC library of NETLIB. One possible download
site is:

    http://lifschitz.physics.odu.edu/slatec

The Digital Signal Processing Group at Rice University offers
Polynomial Root Finder (PRF) written in C as well as a MATLAB
executable.

    http://www.dsp.rice.edu/software/PRF

A good review of more modern (and likely more efficient) methods may
be found at:

    http://citeseer.nj.nec.com/192555.html

            73, Barry L. Ornitz WA4VZQ ornitz_at_tricon.net
Received on Sun Oct 01 2000 - 18:14:25 EDT