Hi,
since ParaView currently doesn’t support the transformation of results to user-defined (mainly cylindrical) coordinate systems, it can only be done manually, by applying proper conversion formulas. However, for cylindrical and spherical coordinates this workaround requires the availability of the atan2 function. The calculator filter doesn’t support it so I suggest adding it to allow for this workaround necessary until the transformation to local coordinate systems is developed. Theoretically, one could use the equivalent arctan2 function in Python Calculator but it’s not very convenient, especially since there are issues with accessing the coordinates.