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function Problem = SJget (matrix, SJ_Index, refresh_mat)
%SJGET loads a matrix from the SJSU Singular Matrix Collection.
%
% Problem = SJget(matrix) loads a matrix from the SJSU Singular matrix collection,
% specified as either a number (1 to the # of matrices in the collection) or
% as a string (the name of the matrix). With no input parameters, index=SJget
% returns an index of matrices in the collection. A local copy of the matrix
% is saved (be aware that as of August 2008 the entire collection is over 1GB
% in size). If no input or output arguments are provided, the index is
% printed. With a 2nd parameter (Problem = SJget (matrix, index)), the index
% file is not loaded. This is faster if you are loading lots of matrices.
% Also SJget('refresh') will force downloading the index file from the
% SJsingular web site. SJget(matrix,'refresh') or
% SJget(matrix,index,'refresh') will force downloading Problem
% matrix from the SJsingular web site, rather than using a
% locally stored copy.
%
% Examples:
% index = SJget ; % loads index of the collection
% index = SJget ('refresh') ; % forces download of new index
% % from the SJsingular web site
% Problem = SJget (6) % get the 6th problem
% Problem = SJget ('HB/ash292') % get a problem by name
% Problem = SJget (6,'refresh') % forces download of 6th problem
% % from the SJSingular web site
% Problem = SJget (6, index) % alternatives to get problems
% Problem = SJget ('HB/ash292', index)
% Problem = SJget (6,index,'refresh') % forces download of 6th problem
% % from the SJsingular web site
%
% or one can search using SJget:
%
% index = SJget ; % get index of the SJSU Singular Matrix Collection
% ids = find (1000 <= index.numrank & index.numrank <= 1200) ;
% [ignore, i] = sort (index.numrank (ids)) ; %sort by numrank
% ids = ids (i) ;
% for id = ids
% Prob = SJget (id); % Prob is a struct (matrix, name, meta-data, ...)
% A = Prob.A ; % A has numerical rank between 1000 and 1200
% disp([index.numrank(id), size(A)]) % list the numerical rank and
% % size of A
% end
% See also SJgrep, SJweb, SJget_example, SJget_defaults, urlwrite.
% spqr_rank, Copyright (c) 2012, Leslie Foster and Timothy A Davis.
% All Rights Reserved.
% SPDX-License-Identifier: BSD-3-clause
%-------------------------------------------------------------------------------
% get the parameter settings
%-------------------------------------------------------------------------------
params = SJget_defaults ;
indexfile = sprintf ('%sSJ_Index.mat', params.dir) ;
indexurl = sprintf ('%s/SJ_Index.mat', params.url) ;
%-------------------------------------------------------------------------------
% get the index file (download a new one if necessary)
%-------------------------------------------------------------------------------
refresh_matrix = 0;
if nargin >= 2
% SJget (..,'refresh') forces downloading matrix .. from the web
if (ischar (SJ_Index))
if (strcmp(SJ_Index, 'refresh'))
refresh_matrix = 1;
end
end
end
if nargin == 3
% SJget (..,..,'refresh') forces downloading matrix .. from the web
if (ischar (refresh_mat))
if (strcmp (refresh_mat, 'refresh'))
refresh_matrix = 1 ;
end
end
end
refresh = 0 ;
if nargin == 0
% if the user passed in a zero or no argument at all, return the index file
matrix = 0 ;
else
% SJget ('refresh') downloads the latest index file from the web
if (ischar (matrix))
if (strcmp (matrix, 'refresh'))
matrix = 0 ;
refresh = 1 ;
end
end
end
if (~refresh)
try
% load the existing index file
if (nargin < 2 )
load (indexfile) ;
end
if (nargin == 2 && refresh_matrix == 1)
load (indexfile) ;
end
% see if the index file is old; if so, download a fresh copy
refresh = (SJ_Index.DownloadTimeStamp + params.refresh < now) ;
catch
% oops, no index file. download it.
refresh = 1 ;
end
end
if (refresh)
% a new SJ_Index.mat file to get access to new matrices (if any)
fprintf ('downloading %s\n', indexurl) ;
fprintf ('to %s\n', indexfile) ;
urlwrite (indexurl, indexfile) ;
load (indexfile) ;
SJ_Index.DownloadTimeStamp = now ;
save (indexfile, 'SJ_Index') ;
end
%-------------------------------------------------------------------------------
% return the index file if requested
%-------------------------------------------------------------------------------
% if the user passed in a zero or no argument at all, return the index file
if nargin == 0
matrix = 0 ;
end
if (matrix == 0)
if (nargout == 0)
% no output arguments have been passed, so print the index file
fprintf ('\nSJSU Singular matrix collection index: %s\n', ...
SJ_Index.LastRevisionDate) ;
fprintf ('\nLegend:\n') ;
fprintf ('num. rank: numerical rank \n') ;
fprintf ('struc. rank: structural rank \n') ;
fprintf ('type: real\n') ;
fprintf (' complex\n') ;
fprintf (' binary: all entries are 0 or 1\n') ;
nmat = length (SJ_Index.nrows) ;
for j = 1:nmat
if (mod (j, 25) == 1)
fprintf ('\n') ;
fprintf ('ID Group/Name nrows-by- ncols num. rank struct. rank type\n') ;
end
s = sprintf ('%s/%s', SJ_Index.Group {j}, SJ_Index.Name {j}) ;
fprintf ('%4d %-30s %7d-by-%7d %10d ', ...
j, s, SJ_Index.nrows (j), SJ_Index.ncols (j), SJ_Index.numrank (j)) ;
%psym = SJ_Index.pattern_symmetry (j) ;
%nsym = SJ_Index.numerical_symmetry (j) ;
fprintf('%13d ', SJ_Index.sprank (j) );
%if (psym < 0)
% fprintf (' - ') ;
%else
% fprintf (' %4.2f', psym) ;
%end
%if (nsym < 0)
% fprintf (' - ') ;
%else
% fprintf (' %4.2f', nsym) ;
%end
if (SJ_Index.isBinary (j))
fprintf (' binary\n') ;
elseif (~SJ_Index.isReal (j))
fprintf (' complex\n') ;
else
fprintf (' real\n') ;
end
end
else
Problem = SJ_Index ;
end
return ;
end
%-------------------------------------------------------------------------------
% determine if the matrix parameter is a matrix index or name
%-------------------------------------------------------------------------------
[group matrix id] = SJget_lookup (matrix, SJ_Index) ;
if (id == 0)
error ('invalid matrix') ;
end
%-------------------------------------------------------------------------------
% download the matrix (if needed) and load it into MATLAB
matdir = sprintf ('%s%s%s%s.mat', params.dir, group) ;
matfile = sprintf ('%s%s%s.mat', matdir, filesep, matrix) ;
maturl = sprintf ('%s/%s/%s.mat', params.url, group, matrix) ;
if (~exist (matdir, 'dir'))
mkdir (matdir) ;
end
if (exist (matfile, 'file') && refresh_matrix == 0)
load (matfile)
else
fprintf ('downloading %s\n', maturl) ;
fprintf ('to %s\n', matfile) ;
urlwrite (maturl, matfile) ;
load (matfile)
save (matfile, 'Problem') ;
end
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