I have a real-valued function of four variables, namely $L[\phi, m0, m1, m2]$. I am interested in taking the partial derivative $\partial_{\phi}L$ thereof and setting the partial derivative to zero, that is $\partial_{\phi}L = 0$. Then solving for $\phi \in [0,2\pi]$ in terms of $m0, m1, m2 \in \mathbb{N}_{0}$. I have reached the point in the attached code where I have generated the partial derivative $\partial_{\phi}L$, but I am having difficulty setting the partial derivative to zero and ge...
