% Script TryFillIn.m
% lu factorization to see fill in for some test matrices

close all; clear all;
A = gallery('poisson',10);
[L,U,P] = lu(A);
spy(L);
figure;
spy(U);
figure;
spy(A);
B = gallery('wathen',10,10);
[M,V,Q] = lu(B);
figure;
spy(M);
figure;
spy(V);
figure;
spy(B);

% now try with luinc
%A = gallery('poisson',10);
[L,U,P] = luinc(A,1e-2);
figure;
spy(L);
figure;
spy(U);
figure;
spy(A);
%B = gallery('wathen',10,10);
[M,V,Q] = luinc(B,1e-2);
figure;
spy(M);
figure;
spy(V);
figure;
spy(B);