Implementing a new recovery scheme for primitive variables in the general relativistic magnetohydrodynamic code Spritz

General relativistic magnetohydrodynamic (GRMHD) simulations represent a fundamental tool to probe various underlying mechanisms at play during binary neutron star (BNS) and (NS) - black hole (BH) mergers. Contemporary flux-conservative GRMHD codes numerically evolve set of conservative equations based on `conserved' variables which then need be converted back into the (`primitive') variables. The corresponding conservative-to-primitive variable recovery procedure, root-finding algorithms, constitutes one core elements such codes. Recently, new robust, accurate efficient scheme called RePrimAnd was introduced, has demonstrated ability always converge unique solution. provides fine-grained error policies handle invalid states caused by evolution errors, also analytical bounds for all primitive In this work, we describe technical aspects implementing code Spritz. To check our implementation as well assess features scheme, perform number tests in three dimensions. Our tests, include critical cases NS collapse BH early (~50 ms) Fishbone-Moncrief BH-accrection disk system, show that is able support magnetized, low density environments with magnetic-to-fluid pressure ratios high 10^4, situations where previously used fails.