NAME<\/a>
SYNOPSIS<\/a>
DESCRIPTION<\/a>
RETURN VALUE<\/a>
ERRORS<\/a>
EXAMPLES<\/a>
APPLICATION USAGE<\/a>
RATIONALE<\/a>
FUTURE DIRECTIONS<\/a>
SEE ALSO<\/a>
COPYRIGHT<\/a> <\/p>\n
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PROLOG <\/a> <\/h2>\nThis manual page is part of the POSIX Programmer\u2019s Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.<\/p>\n
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NAME <\/a> <\/h2>\ntgamma, tgammaf, tgammal \u2014 compute gamma() function<\/p>\n
SYNOPSIS <\/a> <\/h2>\n#include <\/p>\ndouble tgamma(double x<\/i>);
float tgammaf(float x<\/i>);
long double tgammal(long double x<\/i>);<\/p>\nDESCRIPTION <\/a> <\/h2>\nThe functionality described on this reference page is aligned with the ISO\u00a0C standard. Any conflict between the requirements described here and the ISO\u00a0C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO\u00a0C standard.<\/p>\n
These functions shall compute $\u0393 ( ^ x )$ where $\u0393 ( ^ x )$ is defined as $int from 0 to inf e”^” ” “{ – t } t”^” ” “{ x – 1 } dt$.<\/p>\n
An application wishing to check for error situations should set errno<\/i> to zero and call feclearexcept<\/i>(FE_ALL_EXCEPT) before calling these functions. On return, if errno<\/i> is non-zero or fetestexcept<\/i>(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.<\/p>\nRETURN VALUE <\/a> <\/h2>\nUpon successful completion, these functions shall return the gamma of x<\/i>.<\/p>\n
If x<\/i> is a negative integer, a domain error may occur and either a NaN (if supported) or an implementation-defined value shall be returned. On systems that support the IEC 60559 Floating-Point option, a domain error shall occur and a NaN shall be returned.<\/p>\n
If x<\/i> is \u00b10, tgamma<\/i>(), tgammaf<\/i>(), and tgammal<\/i>() shall return \u00b1HUGE_VAL, \u00b1HUGE_VALF, and \u00b1HUGE_VALL, respectively. On systems that support the IEC 60559 Floating-Point option, a pole error shall occur; otherwise, a pole error may occur.<\/p>\n
If the correct value would cause overflow, a range error shall occur and tgamma<\/i>(), tgammaf<\/i>(), and tgammal<\/i>() shall return \u00b1HUGE_VAL, \u00b1HUGE_VALF, or \u00b1HUGE_VALL, respectively, with the same sign as the correct value of the function.<\/p>\n
If the correct value would cause underflow, and is not representable, a range error may occur, and tgamma<\/i>(), tgammaf<\/i>(), and tgammal<\/i>() shall return 0.0, or (if IEC 60559 Floating-Point is not supported) an implementation-defined value no greater in magnitude than DBL_MIN, FLT_MIN, and LDBL_MIN, respectively.<\/p>\n
If the correct value would cause underflow, and is representable, a range error may occur and the correct value shall be returned.<\/p>\n
If x<\/i> is subnormal and 1\/x<\/i> is representable, 1\/x<\/i> should be returned.<\/p>\n
If x<\/i> is NaN, a NaN shall be returned.<\/p>\n
If x<\/i> is +Inf, x<\/i> shall be returned.<\/p>\n
If x<\/i> is \u2212Inf, a domain error shall occur, and a NaN shall be returned.<\/p>\nERRORS <\/a> <\/h2>\nThese functions shall fail if:
Domain\u00a0Error<\/p>\n
The value of x<\/i> is a negative integer, or x<\/i> is \u2212Inf.<\/p>\n
If the integer expression (math_errhandling<\/i> & MATH_ERRNO) is non-zero, then errno<\/i> shall be set to [EDOM]<\/b>. If the integer expression (math_errhandling<\/i> & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised.<\/p>\n
<\/p>\ntgamma, tgammaf, tgammal \u2014 compute gamma() function<\/p>\n
SYNOPSIS <\/a> <\/h2>\n#include <\/p>\ndouble tgamma(double x<\/i>);
float tgammaf(float x<\/i>);
long double tgammal(long double x<\/i>);<\/p>\nDESCRIPTION <\/a> <\/h2>\nThe functionality described on this reference page is aligned with the ISO\u00a0C standard. Any conflict between the requirements described here and the ISO\u00a0C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO\u00a0C standard.<\/p>\n
These functions shall compute $\u0393 ( ^ x )$ where $\u0393 ( ^ x )$ is defined as $int from 0 to inf e”^” ” “{ – t } t”^” ” “{ x – 1 } dt$.<\/p>\n
An application wishing to check for error situations should set errno<\/i> to zero and call feclearexcept<\/i>(FE_ALL_EXCEPT) before calling these functions. On return, if errno<\/i> is non-zero or fetestexcept<\/i>(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.<\/p>\nRETURN VALUE <\/a> <\/h2>\nUpon successful completion, these functions shall return the gamma of x<\/i>.<\/p>\n
If x<\/i> is a negative integer, a domain error may occur and either a NaN (if supported) or an implementation-defined value shall be returned. On systems that support the IEC 60559 Floating-Point option, a domain error shall occur and a NaN shall be returned.<\/p>\n
If x<\/i> is \u00b10, tgamma<\/i>(), tgammaf<\/i>(), and tgammal<\/i>() shall return \u00b1HUGE_VAL, \u00b1HUGE_VALF, and \u00b1HUGE_VALL, respectively. On systems that support the IEC 60559 Floating-Point option, a pole error shall occur; otherwise, a pole error may occur.<\/p>\n
If the correct value would cause overflow, a range error shall occur and tgamma<\/i>(), tgammaf<\/i>(), and tgammal<\/i>() shall return \u00b1HUGE_VAL, \u00b1HUGE_VALF, or \u00b1HUGE_VALL, respectively, with the same sign as the correct value of the function.<\/p>\n
If the correct value would cause underflow, and is not representable, a range error may occur, and tgamma<\/i>(), tgammaf<\/i>(), and tgammal<\/i>() shall return 0.0, or (if IEC 60559 Floating-Point is not supported) an implementation-defined value no greater in magnitude than DBL_MIN, FLT_MIN, and LDBL_MIN, respectively.<\/p>\n
If the correct value would cause underflow, and is representable, a range error may occur and the correct value shall be returned.<\/p>\n
If x<\/i> is subnormal and 1\/x<\/i> is representable, 1\/x<\/i> should be returned.<\/p>\n
If x<\/i> is NaN, a NaN shall be returned.<\/p>\n
If x<\/i> is +Inf, x<\/i> shall be returned.<\/p>\n
If x<\/i> is \u2212Inf, a domain error shall occur, and a NaN shall be returned.<\/p>\nERRORS <\/a> <\/h2>\nThese functions shall fail if:
Domain\u00a0Error<\/p>\n
The value of x<\/i> is a negative integer, or x<\/i> is \u2212Inf.<\/p>\n
If the integer expression (math_errhandling<\/i> & MATH_ERRNO) is non-zero, then errno<\/i> shall be set to [EDOM]<\/b>. If the integer expression (math_errhandling<\/i> & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised.<\/p>\n
double tgamma(double x<\/i>); The functionality described on this reference page is aligned with the ISO\u00a0C standard. Any conflict between the requirements described here and the ISO\u00a0C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO\u00a0C standard.<\/p>\n These functions shall compute $\u0393 ( ^ x )$ where $\u0393 ( ^ x )$ is defined as $int from 0 to inf e”^” ” “{ – t } t”^” ” “{ x – 1 } dt$.<\/p>\n An application wishing to check for error situations should set errno<\/i> to zero and call feclearexcept<\/i>(FE_ALL_EXCEPT) before calling these functions. On return, if errno<\/i> is non-zero or fetestexcept<\/i>(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.<\/p>\n Upon successful completion, these functions shall return the gamma of x<\/i>.<\/p>\n If x<\/i> is a negative integer, a domain error may occur and either a NaN (if supported) or an implementation-defined value shall be returned. On systems that support the IEC 60559 Floating-Point option, a domain error shall occur and a NaN shall be returned.<\/p>\n If x<\/i> is \u00b10, tgamma<\/i>(), tgammaf<\/i>(), and tgammal<\/i>() shall return \u00b1HUGE_VAL, \u00b1HUGE_VALF, and \u00b1HUGE_VALL, respectively. On systems that support the IEC 60559 Floating-Point option, a pole error shall occur; otherwise, a pole error may occur.<\/p>\n If the correct value would cause overflow, a range error shall occur and tgamma<\/i>(), tgammaf<\/i>(), and tgammal<\/i>() shall return \u00b1HUGE_VAL, \u00b1HUGE_VALF, or \u00b1HUGE_VALL, respectively, with the same sign as the correct value of the function.<\/p>\n If the correct value would cause underflow, and is not representable, a range error may occur, and tgamma<\/i>(), tgammaf<\/i>(), and tgammal<\/i>() shall return 0.0, or (if IEC 60559 Floating-Point is not supported) an implementation-defined value no greater in magnitude than DBL_MIN, FLT_MIN, and LDBL_MIN, respectively.<\/p>\n If the correct value would cause underflow, and is representable, a range error may occur and the correct value shall be returned.<\/p>\n If x<\/i> is subnormal and 1\/x<\/i> is representable, 1\/x<\/i> should be returned.<\/p>\n If x<\/i> is NaN, a NaN shall be returned.<\/p>\n If x<\/i> is +Inf, x<\/i> shall be returned.<\/p>\n If x<\/i> is \u2212Inf, a domain error shall occur, and a NaN shall be returned.<\/p>\n These functions shall fail if: The value of x<\/i> is a negative integer, or x<\/i> is \u2212Inf.<\/p>\n If the integer expression (math_errhandling<\/i> & MATH_ERRNO) is non-zero, then errno<\/i> shall be set to [EDOM]<\/b>. If the integer expression (math_errhandling<\/i> & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised.<\/p>\n
float tgammaf(float x<\/i>);
long double tgammal(long double x<\/i>);<\/p>\nDESCRIPTION <\/a> <\/h2>\n
RETURN VALUE <\/a> <\/h2>\n
ERRORS <\/a> <\/h2>\n
Domain\u00a0Error<\/p>\n