n = 5;
nb = 2;

A = rand( n, n );
A = A + A';

L = rand( n, n );

C = tril(L)' * Symm_l( A ) * tril( L );

Cnew = LHAL_blk_var3( A, L, nb );

tril( C ) - tril( Cnew ) + triu( A, 1 ) - triu( Cnew, 1 )
