weakbasis - maxplus matrix image weak basis
B is the weak basis of Im(A) (up to precision pre).
a=#([2,0;0,1]); b=weakbasis(a) a=#([2,0,1;0,1,1]); b=weakbasis(a) a=#([2,0,1,0;0,1,1,%0]); b=weakbasis(a)