tgamma, tgammaf, tgammal: skutečná funkce gama

Originální popis anglicky: tgamma, tgammaf, tgammal - true gamma function

Návod, kniha: libc math functions

STRUČNĚ

#include <math.h> double tgamma(double x); float tgammaf(float x); long double tgammal(long double x); Link with -lm.

POPIS / INSTRUKCE

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.

CHYBY / ERRORY

In order to check for errors, set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred. A range error occurs if x is too large. A pole error occurs if x is zero. A domain error (or a pole error) occurs if x is a negative integer.

ODPOVÍDAJÍCÍ

C99.

SOUVISEJÍCÍ

gamma(3), lgamma(3)