Mercurial > octave
view scripts/polynomial/compan.m @ 31238:67cad4e8f866
Include graphics objects with hidden handles in axes limit calculation (bug #63095).
* libinterp/corefcn/graphics.cc (get_children_limits): Get handles to all axes
children including those with hidden handle visibility. Add BIST.
* libinterp/corefcn/graphics.in.h (text::update_position): Do not automatically
change "zliminclude" property. Axes labels are implemented as text objects, and
we don't want their extent to be included in the axis limit calculation.
author | Markus Mützel <markus.muetzel@gmx.de> |
---|---|
date | Sat, 24 Sep 2022 11:57:44 +0200 |
parents | 5d3faba0342e |
children | 597f3ee61a48 |
line wrap: on
line source
######################################################################## ## ## Copyright (C) 1994-2022 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## This file is part of Octave. ## ## Octave 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 3 of the License, or ## (at your option) any later version. ## ## Octave 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 Octave; see the file COPYING. If not, see ## <https://www.gnu.org/licenses/>. ## ######################################################################## ## -*- texinfo -*- ## @deftypefn {} {@var{A} =} compan (@var{c}) ## Compute the companion matrix corresponding to polynomial coefficient vector ## @var{c}. ## ## The companion matrix is ## @tex ## $$ ## A = \left[\matrix{ ## -c_2/c_1 & -c_3/c_1 & \cdots & -c_N/c_1 & -c_{N+1}/c_1\cr ## 1 & 0 & \cdots & 0 & 0 \cr ## 0 & 1 & \cdots & 0 & 0 \cr ## \vdots & \vdots & \ddots & \vdots & \vdots \cr ## 0 & 0 & \cdots & 1 & 0}\right]. ## $$ ## @end tex ## @ifnottex ## @c Set example in small font to prevent overfull line ## ## @smallexample ## @group ## _ _ ## | -c(2)/c(1) -c(3)/c(1) @dots{} -c(N)/c(1) -c(N+1)/c(1) | ## | 1 0 @dots{} 0 0 | ## | 0 1 @dots{} 0 0 | ## A = | . . . . . | ## | . . . . . | ## | . . . . . | ## |_ 0 0 @dots{} 1 0 _| ## @end group ## @end smallexample ## ## @end ifnottex ## The eigenvalues of the companion matrix are equal to the roots of the ## polynomial. ## @seealso{roots, poly, eig} ## @end deftypefn function A = compan (c) if (nargin != 1) print_usage (); endif if (! isvector (c)) error ("compan: C must be a vector"); endif n = length (c); if (n == 1) A = []; else A = diag (ones (n-2, 1), -1); A(1,:) = -c(2:n) / c(1); endif endfunction %!assert (compan ([1, 2, 3]), [-2, -3; 1, 0]) %!assert (compan ([1; 2; 3]), [-2, -3; 1, 0]) %!assert (isempty (compan (4))) %!assert (compan ([3, 2, 1]), [-2/3, -1/3; 1, 0]) %!error compan ([1,2;3,4]) %!error compan ([])