VMS Help RTL Routines, MTH$, MTH$xREAL, Returns  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    OpenVMS usage:floating_point
    type:         F_floating, D_floating, G_floating
    access:       write only
    mechanism:    by value

    Real part of the complex number. MTH$REAL returns an F-floating
    number. MTH$DREAL returns a D-floating number. MTH$GREAL returns
    a G-floating number.