Solve function returns Warning and empty matrix

I run this code to solve for u and v

syms u v

S = solve([2*u + v == 0, u - v == 1], [u, v])

I get warning saying I have 4 equations and 2 unknowns and a warning that says it cannot find an explicit solution when there is a clear solution to the system. I have other codes that I try to use solve and get the same warnings.

Is there a toolbox I need to download or why can't I use solve?

[Walter Roberson]

As an experiment try

S = solve([2*u + v, u - v - 1], [u, v])

If that works then you might be running an older version of MATLAB that does not handle "==" for symbolic variables.

Answer 1

[Eric Lin]

To add to Walter's answer, the "==" notation was introduced in R2012a: R2012a Release Notes - New Relational Operators Create Equations, Inequalities, and Relations