If h is not a CVX variable or expression, the Laplace operator has nothing to do with CVX. if it is a CVX variable or expression, you will have to figure out “on your own” (i.e., outside of CVX) what it is. And is needs to follow CVX 's rules, for instance being affine in CVX variables. If the expression is not (jointly) convex in the CVX variables, CVX can’t be used at all.