__device__ double lgamma ( double  x  ) 

Calculate the natural logarithm of the gamma function of the input argument x, namely the value of $\log_{e}\left|\int_{0}^{\infty} e^{-t}t^{x-1}dt\right|$

Returns:
  • lgamma(1) returns +0.
  • lgamma(2) returns +0.
  • lgamma(x) returns $\pm \infty$ if the correctly calculated value is outside the double floating point range.
  • lgamma(x) returns $+\infty$ if x $\le$ 0.
  • lgamma($-\infty$) returns $-\infty$.
  • lgamma($(+\infty$) returns $+\infty$.
Note:
For accuracy information for this function see the CUDA C Programming Guide, Appendix C, Table C-2.


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