Set_to_lower_triangular_matrix_unb.m

% Copyright 2023 The University of Texas at Austin
%
% For licensing information see
%                http://www.cs.utexas.edu/users/flame/license.html 
%                                                                                 
% Programmed by: Anni Liu

% Interpret the function: http://edx-org-utaustinx.s3.amazonaws.com/UT501x/PictureFLAME/PictureFLAME.html

function [ A_out ] = Set_to_lower_triangular_matrix_unb( A )

  [ ATL, ATR, ...
    ABL, ABR ] = FLA_Part_2x2( A, ...
                               0, 0, 'FLA_TL' );

  while ( size( ATL, 1 ) < size( A, 1 ) )

    [ A00,  a01,     A02,  ...
      a10t, alpha11, a12t, ...
      A20,  a21,     A22 ] = FLA_Repart_2x2_to_3x3( ATL, ATR, ...
                                                    ABL, ABR, ...
                                                    1, 1, 'FLA_BR' );

    %------------------------------------------------------------%

    a01 = laff_zerov( a01 );

    %------------------------------------------------------------%

    [ ATL, ATR, ...
      ABL, ABR ] = FLA_Cont_with_3x3_to_2x2( A00,  a01,     A02,  ...
                                             a10t, alpha11, a12t, ...
                                             A20,  a21,     A22, ...
                                             'FLA_TL' );

  end

  A_out = [ ATL, ATR
            ABL, ABR ];

return

% Test the function:
% A = randi([-2,2], 4, 4)
% Set_to_lower_triangular_matrix_unb( A )