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tgamma(3) - tgamma, tgammaf, tgammal, tgamma, tgammaf, tgammal - true gamma function - man 3 tgamma

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TGAMMA(3)                     libc math functions                    TGAMMA(3)



NAME
       tgamma, tgammaf, tgammal - true gamma function

SYNOPSIS
       #include <math.h>

       double tgamma(double x);
       float tgammaf(float x);
       long double tgammal(long double x);

       Link with -lm.

DESCRIPTION
       The Gamma function is defined by

        Gamma(x) = integral from 0 to infinity of t^(x-1) e^-t dt

       It  is  defined  for every real number except for nonpositive integers.
       For nonnegative integral m one has

        Gamma(m+1) = m!

       and, more generally, for all x:

        Gamma(x+1) = x * Gamma(x)

       For x < 0.5 one can use

        Gamma(x) * Gamma(1-x) = PI/sin(PI*x)

       This function returns the value of the Gamma function for the  argument
       x.  It  had to be called "true gamma function" since there is already a
       function gamma() that returns something else.

ERRORS
       In order to check for errors, set(7,n,1 builtins) errno to  zero  and  call  feclearex-
       cept(FE_ALL_EXCEPT) before calling these functions. On return, if(3,n) errno
       is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO |  FE_OVERFLOW  |
       FE_UNDERFLOW) is non-zero, an error(8,n) has occurred.

       A  range  error(8,n)  occurs if(3,n) x is too large.  A pole error(8,n) occurs if(3,n) x is
       zero.  A domain error(8,n) (or a pole error(8,n)) occurs if(3,n) x is a negative inte-
       ger.

CONFORMING TO
       C99.

SEE ALSO
       gamma(3), lgamma(3)



GNU                               2002-08-10                         TGAMMA(3)

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