tf2zp.m

similer program for matlab

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##               Auburn University.  All rights reserved.
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## -*- texinfo -*-
## @deftypefn {Function File} {[@var{zer}, @var{pol}, @var{k}] =} tf2zp (@var{num}, @var{den})
## Converts transfer functions to poles-and-zero representations.
##
## Returns the zeros and poles of the @acronym{SISO} system defined 
## by @var{num}/@var{den}.
## @var{k} is a gain associated with the system zeros.
## @end deftypefn

## Author: A. S. Hodel <[e-mail]>

function [zer, pol, k] = tf2zp (num, den)

  if (nargin == 2)
    if (length (den) > 1)
      pol = roots (den);
    else
      pol = [];
    endif

    if (length (num) > 1)
      zer = roots (num);
    else
      zer = [];
    endif
  else
    print_usage ();
  endif

  k = num(1) / den(1);

endfunction