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function A = ssfull_read (file)
%SSFULL_READ read a full matrix using a subset of Matrix Market format
% This function reads in a file generated by ssfull_write. It cannot read
% arbitrary Matrix Market formatted files. See ssfull_write for a description
% of the file format.
%
% Example:
% x = rand (8)
% ssfull_write ('xfile', x)
% y = ssfull_read ('xfile')
% norm (x-y)
%
% See also mread, mwrite, RBwrite, RBread.
% SuiteSparseCollection, Copyright (c) 2006-2019, Timothy A Davis.
% All Rights Reserved.
% SPDX-License-Identifier: GPL-2.0+
% open the file
f = fopen (file, 'r') ;
if (f < 0)
error (['cannot open: ' file]) ;
end
% ignore the header line - determine real/complex from # of entries in each row
s = fgetl (f) ; %#ok
% read in the # of rows and columns
[siz count] = fscanf (f, '%d %d', 2) ;
if (count ~= 2)
error (['invalid file: ' file]) ;
end
m = siz (1) ;
n = siz (2) ;
% read in the rest of the matrix
A = fscanf (f, '%g') ;
% This is an unfortunate workaround. fscanf in C and MATLAB, and the read
% statement in Fortran, cannot interpret the character strings 'Inf', '-Inf',
% or 'NaN' as the appropriate value. Thus, a special huge value (1e308) is
% used to represent these values (Inf and NaN both become 1e308). A sparse
% matrix typically won't included any Inf's or NaN's, but auxiliary arrays can,
% for some problems. For example, the bounds of an LP can be +Inf or -Inf;
% lo(i) = -Inf means that there is no lower bound on the ith variable.
%
% The identical workaround is used in ssfull_write, mread, mwrite, RBread, and
% RBwrite. 1e308 was chosen because it's close to the largest IEEE double
% precision number of 1.7977e308, and because the string '1e308' is short,
% leading to more compact files. Note that NaN's are treated as +Inf.
A (A == 1e308) = Inf ;
A (A == -1e308) = -Inf ;
% reshape the matrix into its final form
if (length (A) == m*n)
% this is a real matrix
A = reshape (A, m, n) ;
elseif (length (A) == 2*m*n)
% this is a complex matrix
A = reshape (A (1:2:end), m, n) + reshape (A (2:2:end), m, n) * 1i ;
else
error (['invalid file: ' file]) ;
end
% close the file
fclose (f) ;
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