log function for symbol with power

Hi.

Can somebody help me with finding and using a function that perform log in a specific base for a symbol with power??

For ex, if I write:

syms a;

and have: b=a^15;

I want to do loga(b) and get '15'.

How can I do so??

Thanks.

Answer 1

[Walter Roberson]

Call into MuPAD with feval(symengine) or evalin(symengine) to use its log() function: http://www.mathworks.com/help/symbolic/mupad_ref/log.html

This is not the same as the log() you get at the MATLAB interface level.

Answer 2

[Andrei Bobrov]

evalin(symengine,'log(a,a^15)')
feval(symengine,'log',a,a^15)