lgamma
From cppreference.com
| Defined in header
<math.h>
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| float lgammaf( float arg );
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(since C99) | |
| double lgamma( double arg );
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(since C99) | |
| long double lgammal( long double arg );
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(since C99) | |
Computes the natural logarithm of the absolute value of the gamma function of arg.
Contents |
[edit] Parameters
| arg | - | floating point value |
[edit] Return value
The value of the logarithm of the gamma function of arg, that is log
e|∫∞
0targ-1
e-t dt|.
If arg is a natural number, lgamma(arg) is the logarithm of the factorial of arg-1.
[edit] Exceptions
If arg is zero or a negative integer, pole error may occur and FE_INVALID or FE_DIVBYZERO may be raised.
If arg is too large, range error may occur and FE_OVERFLOW may be raised.
[edit] Notes
POSIX specification additionally requires that each execution of lgamma stores the sign of the gamma function of arg in the external variable signgam.
[edit] See also
| (C99)
|
gamma function (function) |
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C++ documentation for lgamma
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[edit] External links
Weisstein, Eric W. "Log Gamma Function." From MathWorld--A Wolfram Web Resource.