Hi, thanks for responding on this. In my post, I mention that I first tried a simple 4eqn 4unk type Solve using an assume on the output. Here's what the old code looked like. I think it will provide a little more context: The Solve statement contains the four equations of the form: sigma[eqn,x] = A*sigma[1] + B*sigma[2] + C*sigma[3] + D*sigma[4] sigma[app,x] is my data which I use to obtain the constants A,B,C,D above. The four sigma[x] variables are my unknowns that I'm solving for. assume(sigma[1] > 0, sigma[2] > 0, sigma[3] > 0, sigma[4] > 0, sigma[1] < 500, sigma[2] < 500, sigma[3] < 500, sigma[4] < 500): Soln := solve({sigma[eqn,1]=sigma[app,1], sigma[eqn,2]=sigma[app,2], sigma[eqn,3]=sigma[app,3], sigma[eqn,4]=sigma[app,4]},{sigma[1],sigma[2],sigma[3],sigma[4]});

Excellent thank you, that worked great =)

I guess I'll try my hardest to find some more then =)

Yep, that is the correct solution (as we obtained by paper and other alternative methods) and is physical. In Maple 10 I also get that solution when I add the assumption of s>0. I guess it was just the concern with maple 6's multiple results then... that is very good to know that further solutions are not correct. Thanks again for your help