can_256.mat'  can_634.mat'  
load('can_634');
A = Problem.A;


[p, ptr, mask]= bfsWithLev(A,1);


B = A(p,p);

spyGrid(B,ptr)
close



help color
  function [colors, p, ptr] = color(A, maxcol)  
  colors = colors of each node
  p = multicoloring permutation
  ptr = ptr to start of each color set

    Folders named color

       graphics/color

[colors, p, ptr] = color(A,30);
B = A(p,p);

spyGrid(B,ptr)
length(ptr)
ans =
    11
close
p = amd(A);



B = A(p,p);
spy(B)



p = dissect(A);


B = A(p,p);
spy(B)
t  = abs(B)*ones(size(B,1));
B = spdiags(t,0,B);
[L U] = lu(B);
spy(L+U)
diary off