Matrix inverse with numbers and letters

Hi Everyone, I need to have a matrix inverse of a matrix which is not only made of numbers. How can I have an inverse of my matrix leaving numbers and letters?

Answer 1

[Rosi]

I´m not sure about what you want to do, but this could be one way for solving your problem.

syms a b c d

A = [a 1 2 b; 0 4 2 10; 5 1 2 c; 4 d 9 3];

A^-1

Answer 2

[John D'Errico]

This gets asked over and over again. Nothing stops you from trying it. The symbolic toolbox can do it, within limits.

While the idea is fine for a 2x2 or 3x3, and perhaps you can go a bit further and gain a usable result. I seriously doubt that you might want to bother for a 10x10 matrix though.

syms a11 a12 a21 a22
A = [a11 a12;a21 a22];
inv(A)

ans =
[  a22/(a11*a22 - a12*a21), -a12/(a11*a22 - a12*a21)]
[ -a21/(a11*a22 - a12*a21),  a11/(a11*a22 - a12*a21)]

So, trivial for a small matrix. Not so at all if your matrix is large.