Best Solver of Nonlinear Equations for Large Matrices

All,

I am solving for a variable in a nonlinear equation using fsolve,fminsearch, etc on MATLAB R2010B. However, this variable is actually a large square matrix. Due to the size of the matrix, it seems that fsolve and fminsearch run out of memory even with the Jacobian. I applied a variety of options to limit the computation time, such as TolFun, MaxIter, MaxFunEvals, etc as well.

I was able to iterate through every entry in the matrix and get an answer using fzero but it was relatively time consuming. I'm wondering if there's an easier solution using either one of the above commands or another command in MATLAB.

Thanks for your help.