function wathen_test04 ( )

%*****************************************************************************80
%
%% WATHEN_TEST04 assembles, factor and solve using WATHEN_DAVIS.
%
%  Licensing:
%
%    This code is distributed under the GNU LGPL license.
%
%  Modified:
%
%    04 June 2014
%
%  Author:
%
%    John Burkardt
%
  fprintf ( 1, '\n' );
  fprintf ( 1, 'WATHEN_TEST04\n' );
  fprintf ( 1, '  Assemble, factor and solve a Wathen system\n' );
  fprintf ( 1, '  defined by WATHEN_DAVIS.\n' );
  fprintf ( 1, '\n' );

  nx = 4;
  ny = 4;
  fprintf ( 1, '  Elements in X direction NX = %d\n', nx );
  fprintf ( 1, '  Elements in Y direction NY = %d\n', ny );
  fprintf ( 1, '  Number of elements = %d\n', nx * ny );
%
%  Compute the number of unknowns.
%
  n = wathen_order ( nx, ny );
  fprintf ( 1, '  Number of nodes N = %d\n', n );
%
%  Set up a random solution X1.
%
  seed = 123456789;
  [ x1, seed ] = r8vec_uniform_01 ( n, seed );
%
%  Compute the matrix.
%
  seed = 123456789;
  [ a, seed ] = wathen_davis ( nx, ny, n, seed );
%
%  Compute the corresponding right hand side B.
%
  b = a * x1;
%
%  Solve the linear system.
%
  x2 = a \ b;
%
%  Compute the maximum solution error.
%
  e = max ( abs ( x1 - x2 ) );
  fprintf ( 1, '  Maximum solution error is %g\n', e );

  return
end


johannesgerer
github-repos/MATLAB/johannesgerer-jburkardt-m/jburkardt-m-1726deb4a34dd08a49c26359d44ef47253f006c1/wathen/wathen_test04.m
jburkardt-m
github-repos/MATLAB/johannesgerer-jburkardt-m
1726deb4a34dd08a49c26359d44ef47253f006c1