# Question:Simultaneous equations problems with solve

## Question:Simultaneous equations problems with solve

Maple

Hi there,

I'm trying to solve a set of simultaneous equations using the solve function, but it doesn't seem to want to give me a straight answer (and sometimes no answer at all).

Here are my equations, which were derived in Maple and have been tested in Matlab, I've pasted Matlab code generated versions here as I couldn't seem to copy and paste from Maple to this form? I also can't upload my example worksheet, the browser comes up with a script error whenever I try (never had this problem before...). I'm trying to solve for q3 and q4, all other terms are known (including q1 and q2). q3 and q4 have unique solutions as this is a robot kinematics problem and has been verified numerically.

Wx = ((-sin(q1) * sin(q2) * sin(q3) - cos(q1) * cos(q3)) * sin(q4) - sin(q1) * cos(q2) * cos(q4)) * L3 - sin(q1) * cos(q2) * L21;
Wy = (-cos(q2) * sin(q3) * sin(q4) + sin(q2) * cos(q4)) * L3 + sin(q2) * L21;
Wz = ((-cos(q1) * sin(q2) * sin(q3) + sin(q1) * cos(q3)) * sin(q4) - cos(q1) * cos(q2) * cos(q4)) * L3 - cos(q1) * cos(q2) * L21;

solve({Wx,Wy,Wz},[q3,q4]) produces no output, i.e: '[]'
solve({Wy},[q3,q4]) gives me an equation for q3 containing q4 (fair enough with only Wy to work with!) but states that q4=q4.
solve({Wy,Wz},[q3,q4]) looks promising but RootOf appears throughout and a _Z term has appeared?

Could someone please explain what is going on?
I thought this would be an easy problem to solve with Maple?!

Many Thanks,