Symbolic matrix algebra calculation
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I want to do some algebra with matrices. However when I would create
A = sym('A',2)
B = sym('B',2)
[ A2_2/(A1_1*A2_2 - A1_2*A2_1), -A1_2/(A1_1*A2_2 - A1_2*A2_1)]
[ -A2_1/(A1_1*A2_2 - A1_2*A2_1), A1_1/(A1_1*A2_2 - A1_2*A2_1)]
Roles out. While I still want it to be A*B. Now I cannot use normal symbolic variables since they change the order of the multiplication, which is normally not allowed with matrices.
syms a b
(a + b)*b
b*(a + b)
Which is not correct for matrices. Is it possible to create symbolic variables which do not change the order?
Roger Stafford on 26 Sep 2014
Edited: Roger Stafford on 26 Sep 2014
If you use the form a = sym('a',n) or a = sym('a',[m.n]) to declare symbolic vectors or matrices, I seriously doubt that the order of multiplication with other such symbolic vectors or matrices will ever be reversed, so that is presumably what you have to do to handle your algebra. Note that without such detailed descriptions as to size, matlab would not be able to recognize when a proposed multiplication was improper due to non-matching inner dimensions.