exampleunsym

 This is an example script demonstrating how PARDISO works on a small,
 sparse, real non-symmetric matrix. It computes the m solutions X to the
 collection of linear systems

    A * X = B

 using the PARDISO solver, where A is a symmetric n x n matrix, B is an
 n x m matrix, and X is another n x m matrix.

0001 % This is an example script demonstrating how PARDISO works on a small,
0002 % sparse, real non-symmetric matrix. It computes the m solutions X to the
0003 % collection of linear systems
0004 %
0005 %    A * X = B
0006 %
0007 % using the PARDISO solver, where A is a symmetric n x n matrix, B is an
0008 % n x m matrix, and X is another n x m matrix.
0009 clear
0010 verbose = false;
0011 
0012 dkepath = load_structures_yp('dkepath','','');
0013 
0014 n = 4;  % The number of equations.
0015 m = 3;  % The number of right-hand sides.
0016 
0017 A = sparse([  0 -2  3 0
0018              -2  4 -4 1
0019              -3  5  1 1
0020               1 -3  0 2 ]);
0021 
0022 % Generate a random collection of right-hand sides.
0023 B = ones(n,m);
0024 
0025 % Initialize the PARDISO internal data structures. We've told PARDISO to
0026 % handle real non-symmetric matrices using the sparse direct solver.
0027 info = pardisoinit(11,0);
0028 
0029 % Analyze the matrix and compute a symbolic factorization.
0030 info = pardisoreorder(A,info,verbose);
0031 fprintf('The factors have %d nonzero entries.\n',info.iparm(18));
0032 
0033 % Compute the numeric factorization.
0034 info = pardisofactor(A,info,verbose);
0035 
0036 % Compute the solutions X using the symbolic factorization.
0037 [X info] = pardisosolve(A,B,info,verbose);
0038 fprintf('PARDISO performed %d iterative refinement steps.\n',info.iparm(7));
0039 
0040 % Compute the residuals.
0041 R = max(abs(A*X - B));
0042 fprintf('The maximum residual for the solution X is %0.3g.\n',max(R(:)));
0043 
0044 % Free the PARDISO data structures.
0045 % pardisofree(info);
0046 % clear info