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

 angle-in-radians

    OpenVMS usage:floating_point
    type:         F_floating, D_floating, G_floating
    access:       read only
    mechanism:    by reference

    Angle (in radians). The angle-in-radians argument is the address
    of a floating-point number that is this angle. For MTH$SIN,
    angle-in-radians specifies an F-floating number. For MTH$DSIN,
    angle-in-radians specifies a D-floating number. For MTH$GSIN,
    angle-in-radians specifies a G-floating number.