Regularity results for generalized double phase functionals

We consider a wide class of functionals with the property of changing their growth and ellipticity properties according to the modulating coefficients in the framework of Musielak-Orlicz spaces. In particular, we provide an optimal condition on the modulating coefficient to establish the Holder regularity and Harnack inequality for quasiminimizers of the generalized double phase functional with. G; H/-growth for two Young functions G and H.