showing only real numbers



Hi all

I am doing calculations to find solution concentrations in chemical  
equilibria.  Some of this involves work solving cubics, which I am  
finding yield a lot of imaginary numbers.  Is there perhaps a way to  
make maxima only give the real roots of a cubic, or any other  
polynomial for that matter?  They really just get in the way when  
dealing with real processes.

Regards
Justin Harford