I am solving non-linear PDE using iterations. Correspondingly, the coefficients are functions on the (same) mesh that I have created and fixed. Between iterations I need to update these function by doing some arithmetic operations on them. Just doing all in a straightforward way leads to Mathematica being very slow. So, I have to prepare my PDE coefficients in advance by creating new interpolating functions for them. I do this via, for example
ElementMeshInterpolation[oldfunction["ElementMesh"], oldfunction["ValuesOnGrid"]^2]
ElementMeshInterpolation[oldfunction["ElementMesh"], oldfunction["ValuesOnGrid"]^2]
Is there a smart way to tell Mathematica to create a single interpolating function from arithmetic operations (and derivatives) of several functions on the same grid?