VMS Help RTL Routines, MTH$, MTH$xATAN2  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Given sine and cosine, the Arc Tangent in Radians with Two
    Arguments routine returns the angle (in radians) whose tangent
    is given by the quotient of  sine and cosine (sine/cosine).

    Format

      MTH$ATAN2  sine ,cosine

      MTH$DATAN2  sine ,cosine

      MTH$GATAN2  sine ,cosine

      Each of the above formats accepts one of the floating-point
      types as input.

1 - Returns

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

    Angle in radians. MTH$ATAN2 returns an F-floating number.
    MTH$DATAN2 returns a D-floating number. MTH$GATAN2 returns a
    G-floating number.

2 - Arguments

 sine

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

    Dividend. The sine argument is the address of a floating-point
    number that is this dividend. For MTH$ATAN2, sine specifies an
    F-floating number. For MTH$DATAN2, sine specifies a D-floating
    number. For MTH$GATAN2, sine specifies a G-floating number.

 cosine

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

    Divisor. The cosine argument is the address of a floating-point
    number that is this divisor. For MTH$ATAN2, cosine specifies an
    F-floating number. For MTH$DATAN2, cosine specifies a D-floating
    number. For MTH$GATAN2, cosine specifies a G-floating number.