Evaluating a string in octave

[Doug Stewart]

I have a string in octave that looks like this:
( it was produced with my new Inverse Z Transform function)

+ 15 *  (0.5)^(K)   -35 *  (0.7)^(K)  + 20 *  (1)^(K) 

and I put this string in q

q = + 15 *  (0.5)^(K)   -35 *  (0.7)^(K)  + 20 *  (1)^(K) 


Now I want to give K a value and then evaluate the formula.

K=5
m=evaluate(q)



How do you do this?

Doug