Interface

      F_TYPE lgamma (F_TYPE x)

1  –  Description

    lgamma() returns the logarithm of the absolute value of gamma
    of x, or ln(|G(x)|), where G is the gamma function. The sign of
    gamma of x is returned in the external integer variable signgam
    as +1 or -1. The x parameter cannot be 0 or a negative integer.

    gamma() returns the natural log of the gamma function and so is
    functionally equivalent to lgamma(). Because of this, gamma()  is
    marked TO BE WITHDRAWN in the X/Open Portability Guide, Revision
    4 (XPG4).

                           Entry-Point Names

    Generic
    Function   Data Type   OpenVMS                Tru64 UNIX
    Name       Required

    lgamma     S_FLOAT     math$lgamma_s          lgammaf
               T_FLOAT     math$lgamma_t          lgamma
               X_FLOAT     math$lgamma_x          lgammal
               F_FLOAT     math$lgamma_f
               G_FLOAT     math$lgamma_g

2  –  Exceptions

    Exceptional Argument            Routine Behavior

    |x| = infinity                  Invalid argument
    x = 0, -1, -2, -3, ...          Invalid argument
    |x| > lgamma_max_float          Overflow

    Data
    Type  Value for: lgamma_max_float

    F     Hexadecimal: 50F97CC6
    G     Hexadecimal: F55FC5015ABD7F67
    S     Hexadecimal: 7BC650F9
    T     Hexadecimal: 7F475ABDC501F55F
    X     Hexadecimal: 7FF171AA9917FFFBD7EA44AE6D203DF6

    F     Decimal: 2.0594342e36
    G     Decimal: 1.2812545499066958e305
    S     Decimal: 2.0594342e36
    T     Decimal: 1.2812545499066958e305
    X     Decimal: 1.0485738685148938358098967157129705040168e4928