sdmmat.m

来自「这是matlab解2阶锥工具包」· M 代码 · 共 51 行

function Y = sdmmat(x,m)
% SDMMAT - given a vector x, produces a matrix Y s.t. x = vec(Y).
%  
% Y = sdmmat(x,m)   or   Y = sdmmat(x)   (the 2nd argument is optional)
%  
%   Given a vector of length m*n (default n=m)
%   this produces the m x n sparse matrix Y such that x = vec(Y).
%   In other words, x contains the columns of the
%   matrix Y, stacked below each other.
%
% SEE ALSO vec, mat and sdmvec.
  
%   This file is part of SeDuMi Interface 1.04 (JUL2002)
%   Last update : 9th September 2002
%   Copyright (C) 2002 Dimitri Peaucelle & Krysten Taitz
%   LAAS-CNRS, Toulouse, France
% 
%   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., 675 Mass Ave, Cambridge, MA 02139, USA.
   
if nargin < 2
  n = floor(sqrt(length(x)));
  m=n;
  if (n*n) ~= length(x)
    error('the input argument must be a vector of length n*n')
  end
elseif m<=0
  error('2nd input argument (number of rows) must be a positive integer');
else  
  mn = length(x);
  n = floor(mn/m);
  if (m*n) ~= length(x)
    etext=sprintf(['1st input argument must be a vector of length proportionnal to m\n'...
		  'where m is the 2nd input argument']);
    error(etext);
  end  
end
Y = reshape(x,m,n);