testgauss.m

LU decomposition routines in matlab

%
% testgauss.m
%
%
% Use the Gaussian elimination and LU decomposition 
% to solve a linear system.
% The Gaussian elimination is computed by gauss.m,
% the upper triangular system is solved by utriangsl.m  
%


A = [ 2 4 2
      4 6 8
      1 3 2 ];

b = [  4
      12 
       3 ];

disp( ' The system matrix A  ')
disp( A )
disp( ' and the right hand side vector b ')
disp( b )

disp( ' The solution of A x = b computed using Matlab  A\b')
disp( A\b )


[A,b] = gauss( A, b);


disp( ' The transformed system matrix A  ')
disp( A )
disp( ' and the transformed right hand side vector b ')
disp( b )

[b,iflag] = utriangsl( A, b);

disp( ' The solution of A x = b ')
disp( b )



disp( ' Hit return to continue ... ')
pause




n = 4;
A = ones(n,n);
A(:,2) = (1:n)';
for j = 3:n
    A(:,j) = A(:,j-1) .* A(:,2);
end
b = (1:n)';


[A,b] = gauss( A, b)
[b,iflag] = utriangsl( A, b);

disp( ' The solution of A x = b ')
disp( b )