How do I solve a system of equations involving gamma functions?

I need to write a MATLAB program to solve the following system of equations:

E[A]=(2/b)*gamma(M+0.5)*gamma(m+0.5)/(gamma(m)*gamma(M))

E[A^2]=Mm(2/b)^2

E[A^0.5]=(sqrt(2/b))*gamma(M+0.5)*gamma(m+0.5)/(gamma(m)*gamma(M))

The objective is to find parameters M and m. The E[A] terms are moments that can be found from the given data.

I have tried using the solve() function but ran into problems. Can anyone please help?

[Andrew Sykes]

You might consider using the "fsolve" function.

One potential issue is that your statement of the problem suggests you have 3 equations and 2 unknowns; m and M (unless b is also unknown?). This will mean one of the following

1. one of your three equations is a restatement (i.e. linear combination) of the other equations. This will mean one equation is trivially solved, so you don't need to worry about it.
2. your problem is not well-posed, and no solution exists.