Geant3 to Geant4 migration

Hello community,

I am trying to migrate a Geant3 simulation code into Geant4. Unfortunately, in the Geant3 code, there are several secondary routines like VZERO, UCOPY, GTRMUL, GRMUL, GFANG, GINROT, VSCALE, VADD, VLINE, VUNIT, and CROSS. I suspect they all manipulate arrays, but I don’t know exactly what they do.

Could anyone please help me understand what these Geant3 routines do? I looked for them in the Geant3 manual but there is no information about.

Thanks in advance and have a good day.