Hi all, I'm currently working at a physics research group and I need to find a way to solve an optimization problem with multiple non linear equations. I don't have any significant background, but I've looked in a few books we have around the office and didn't find much - I'm hoping you all can help me out. Barring anything else, suggestions on good books are much appreciated as well. I've got equations of the form $\displaystyle \\ \hat{y}_{n} = k(x_{1} {{a_{1}}^{x_{2}}+ ... +x_{1} {{a_{n}}^{x_{2}}) $ and I'm trying to find the values of $\displaystyle x_{1}$ and $\displaystyle x_{2}$ that minimize the total error $\displaystyle \sum{(y_{n} - \hat{y}_{n})^{2}}$. Can anyone point me in the right direction?