Mercurial > hg > octave-thorsten
changeset 5382:7012c2492c12
[project @ 2005-06-05 13:30:48 by jwe]
author | jwe |
---|---|
date | Sun, 05 Jun 2005 13:30:48 +0000 |
parents | 75f308189a05 |
children | ffea7e58bc00 |
files | scripts/polynomial/polygcd.m |
diffstat | 1 files changed, 4 insertions(+), 69 deletions(-) [+] |
line wrap: on
line diff
--- a/scripts/polynomial/polygcd.m +++ b/scripts/polynomial/polygcd.m @@ -1,68 +1,3 @@ -## Copyright (C) 2000 Paul Kienzle -## -## This program is free software; you can redistribute it and/or modify -## it under the terms of the GNU General Public License as published by -## the Free Software Foundation; either version 2 of the License, or -## (at your option) any later version. -## -## This program is distributed in the hope that it will be useful, -## but WITHOUT ANY WARRANTY; without even the implied warranty of -## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -## GNU General Public License for more details. -## -## You should have received a copy of the GNU General Public License -## along with this program; if not, write to the Free Software -## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA - -## -*- texinfo -*- -## @deftypefn {Function File} {[@var{q}]} polygcd (@var{b}, @var{a}, @var{tol}) -## -## Find greatest common divisor of two polynomials. This is equivalent -## to the polynomial found by multiplying together all the common roots. -## Together with deconv, you can reduce a ratio of two polynomials. -## Tolerance defaults to -## @example -## sqrt(eps). -## @end example -## Note that this is an unstable -## algorithm, so don't try it on large polynomials. -## -## Example -## @example -## polygcd(poly(1:8),poly(3:12)) - poly(3:8) -## deconv(poly(1:8),polygcd(poly(1:8),poly(3:12))) - poly(1:2) -## @end example -## @end deftypefn -## -## @seealso{poly, polyinteg, polyderiv, polyreduce, roots, conv, deconv, -## residue, filter, polyval, and polyvalm} - -function x = polygcd(b,a,tol) - if (nargin<2 || nargin>3) - usage("x=polygcd(b,a [,tol])"); - endif - if (nargin<3), tol=sqrt(eps); endif - if (length(a)==1 || length(b)==1) - if a==0, x=b; - elseif b==0, x=a; - else x=1; - endif - return; - endif - a = a./a(1); - while (1) - [d, r] = deconv(b, a); - nz = find(abs(r)>tol); - if isempty(nz) - x = a; - return; - else - r = r(nz(1):length(r)); - endif - b = a; - a = r./r(1); - endwhile -endfunction ## Copyright (C) 2000 Paul Kienzle ## ## This program is free software; you can redistribute it and/or modify @@ -81,7 +16,7 @@ ## 02110-1301 USA ## -*- texinfo -*- -## @deftypefn {Function File} {[@var{q}]} polygcd (@var{b}, @var{a}, @var{tol}) +## @deftypefn {Function File} {@var{q} =} polygcd (@var{b}, @var{a}, @var{tol}) ## ## Find greatest common divisor of two polynomials. This is equivalent ## to the polynomial found by multiplying together all the common roots. @@ -95,8 +30,8 @@ ## ## Example ## @example -## polygcd(poly(1:8),poly(3:12)) - poly(3:8) -## deconv(poly(1:8),polygcd(poly(1:8),poly(3:12))) - poly(1:2) +## polygcd (poly(1:8), poly(3:12)) - poly(3:8) +## deconv (poly(1:8), polygcd (poly(1:8), poly(3:12))) - poly(1:2) ## @end example ## @end deftypefn ## @@ -129,7 +64,7 @@ r = r(nz(1):length(r)); endif b = a; - a /= r(1); + a = r / r(1); endwhile endif else