load('can_256')
who

Your variables are:

Problem  

Problem
Problem = 
    title: '1SYMMETRIC PATTERN FROM CANNES,LUCIEN MARRO,JUNE 1981.                  '
        A: [256x256 double]
     name: 'HB/can_256'
A = Problem.A;
spy(A)
p = bfs(A,1);


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


[L U] = lu(A);

nnz(L+U)
ans =
       30811
[L U] = lu(B);
nnz(L+U)
ans =
       25426
p = cmk1(A,1);
C = A(p,p);
[L U] = lu(C);
nnz(L+U)
ans =
       19692
nnz(A)
ans =
        2916
p = p (end:-1:1);
C = A(p,p);
[L U] = lu(C);
nnz(L+U)
ans =
       11773


p = cmk1(A,1);
C = A(p,p);
spy(C)

p = p (end:-1:1);
C = A(p,p);
spy(C)



p = symrcm(A);
C = A(p,p);
[L U] = lu(C);
nnz(L+U)
ans =
       10934
p(end)
ans =
   255


p = cmk1(A,255);
p = p(end:-1:1);
C = A(p,p);
nnz(L+U)
ans =
       10934
[L U] = lu(C);
nnz(L+U)
ans =
       10934
p = symamd(A);
C = A(p,p);
[L U] = lu(C);
nnz(L+U)
ans =
        7521
diary off