VMS Help RTL Routines, MTH$, MTH$xCOSD, 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

    Cosine of the angle. MTH$COSD returns an F-floating number.
    MTH$DCOSD returns a D-floating number. MTH$GCOSD returns a G-
    floating number.