Symbolic transpose of a matrix with the dimension not defined

Hello,

I am trying to work with symbolic variables in Matlab but I have a little problem. I want to work with general expressions without specify the dimensions of the matrix. For example if I define A as a symbolic variable and I use "transpose(A)" I want to receive "transpose(A)" and not this:

>> syms A
transpose(A)

ans =

A

>> A = sym('a',[3 3]);
transpose(A) 
ans = 
[ a1_1, a2_1, a3_1]
[ a1_2, a2_2, a3_2]
[ a1_3, a2_3, a3_3]

I have a huge expression that I want to simplify later with the command "simplify".

Thank you in advance, Álvaro

Answer 1

[Walter Roberson]

Perhaps define a symbolic function Tr(M) without giving a definition for it, and apply it as needed. When it comes time to substitute actual matrix dimensions for A, you can also substitute a transpose function for Tr which would trigger the transposes.

[Álvaro]

great! it is working in the way that I want. Thank you for your answer.

I have now another issue. I have a really long symbolic expression that i want to contract using the function horner. Unfortunately it is not working for me and I dont now why. For example when I try do something like this it works

>> syms x y
>> f = x*x + x*y + x*x*x

f =

x^3 + x^2 + y*x

>> horner(f)

ans =

x*(y + x*(x + 1))

>>

but with my expression that it's really similar it doesn't contract the expression. Can you help me?

Thank you again

[Walter Roberson]

horner cannot do much unless it finds something that looks like a monomial . It does not take much to throw off horner.

Often more useful than horner() is collect()

But I would need to see more of the structure of your expression to say more.