%CS_DEMO1 MATLAB version of the CSparse/Demo/cs_demo1.c program.
% Uses both MATLAB functions and CSparse mexFunctions, and compares the two
% results.  This demo also plots the results, which the C version does not do.
%
% Example:
%   cs_demo1
% See also: cs_demo

%   Copyright 2006, Timothy A. Davis.
%   http://www.cise.ufl.edu/research/sparse

load (['..' filesep '..' filesep 'Matrix' filesep 't1']) ;
T = t1
A  = sparse    (T(:,1)+1, T(:,2)+1, T(:,3))
A2 = cs_sparse (T(:,1)+1, T(:,2)+1, T(:,3))
fprintf ('A difference: %g\n', norm (A-A2,1)) ;
% CSparse/Demo/cs_demo1.c also clears the triplet matrix T at this point:
% clear T 
clf
subplot (2,2,1) ; cspy (A) ; title ('A', 'FontSize', 16) ;
AT = A'
AT2 = cs_transpose (A)
fprintf ('AT difference: %g\n', norm (AT-AT2,1)) ;
subplot (2,2,2) ; cspy (AT) ; title ('A''', 'FontSize', 16) ;
n = size (A,2) ;
I = speye (n) ;
C = A*AT ;
C2 = cs_multiply (A, AT)
fprintf ('C difference: %g\n', norm (C-C2,1)) ;
subplot (2,2,3) ; cspy (C) ; title ('C=A*A''', 'FontSize', 16) ;
cnorm = norm (C,1) ;
D = C + I*cnorm
D2 = cs_add (C, I, 1, cnorm)
fprintf ('D difference: %g\n', norm (D-D2,1)) ;
subplot (2,2,4) ; cspy (D) ; title ('D=C+I*norm(C,1)', 'FontSize', 16) ;
% CSparse/Demo/cs_demo1.c clears all matrices at this point:
% clear A AT C D I
% clear A2 AT2 C2 D2