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function x = cs_qrsol (A,b,order) %#ok
%CS_QRSOL solve a sparse least-squares problem.
% x = cs_qrsol(A,b) solves the over-determined least squares problem to
% find x that minimizes norm(A*x-b), where b is a full vector and
% A is m-by-n with m >= n. If m < n, it solves the underdetermined system
% Ax=b. A 3rd input argument specifies the ordering method to use
% (0: natural, 3: amd(A'*A)). The default ordering is 3.
%
% Example:
% Prob = ssget ('HB/well1033') ; A = Prob.A ; [m n] = size (A) ;
% b = rand (m,1) ;
% x1 = cs_qrsol (A,b) ;
% x2 = A\b ;
% norm (x1-x2)
%
% For this example, cs_qrsol is about 3 times faster than A\b in MATLAB 7.3.
%
% See also CS_QR, CS_AMD, CS_LUSOL, CS_CHOLSOL, MLDIVIDE.
% CXSparse, Copyright (c) 2006-2022, Timothy A. Davis. All Rights Reserved.
% SPDX-License-Identifier: LGPL-2.1+
error ('cs_qrsol mexFunction not found') ;
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