From 82ba818ff456bcd6d56a06226e3f27e98fbb55c3 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Thu, 14 Aug 2025 22:58:58 -0500 Subject: removing all downloaded devdocs files --- devdocs/c/numeric%2Fmath%2Flgamma.html | 85 ---------------------------------- 1 file changed, 85 deletions(-) delete mode 100644 devdocs/c/numeric%2Fmath%2Flgamma.html (limited to 'devdocs/c/numeric%2Fmath%2Flgamma.html') diff --git a/devdocs/c/numeric%2Fmath%2Flgamma.html b/devdocs/c/numeric%2Fmath%2Flgamma.html deleted file mode 100644 index 5dbfcbd3..00000000 --- a/devdocs/c/numeric%2Fmath%2Flgamma.html +++ /dev/null @@ -1,85 +0,0 @@ -

lgamma, lgammaf, lgammal

Defined in header <math.h> 
float       lgammaf( float arg );
-		 (1) (since C99) 
double      lgamma( double arg );
-		 (2) (since C99) 
long double lgammal( long double arg );
-		 (3) (since C99)
Defined in header <tgmath.h> 
#define lgamma( arg )
-		 (4) (since C99)
-1-3) Computes the natural logarithm of the absolute value of the gamma function of arg.
-4) Type-generic macro: If arg has type long double, lgammal is called. Otherwise, if arg has integer type or the type double, lgamma is called. Otherwise, lgammaf is called.

Parameters

- -
arg - floating point value

Return value

If no errors occur, the value of the logarithm of the gamma function of arg, that is \(\log_{e}|{\int_0^\infty t^{arg-1} e^{-t} \mathsf{d}t}|\)loge|∫∞0targ-1 e-t dt|, is returned.

-

If a pole error occurs, +HUGE_VAL, +HUGE_VALF, or +HUGE_VALL is returned.

-

If a range error due to overflow occurs, ±HUGE_VAL, ±HUGE_VALF, or ±HUGE_VALL is returned.

-

Error handling

Errors are reported as specified in math_errhandling.

-

If arg is zero or is an integer less than zero, a pole error may occur.

-

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

-

Notes

If arg is a natural number, lgamma(arg) is the logarithm of the factorial of arg - 1.

-

The POSIX version of lgamma is not thread-safe: each execution of the function stores the sign of the gamma function of arg in the static external variable signgam. Some implementations provide lgamma_r, which takes a pointer to user-provided storage for singgam as the second parameter, and is thread-safe.

-

There is a non-standard function named gamma in various implementations, but its definition is inconsistent. For example, glibc and 4.2BSD version of gamma executes lgamma, but 4.4BSD version of gamma executes tgamma.

-

Example

#include <stdio.h>
-#include <math.h>
-#include <float.h>
-#include <errno.h>
-#include <fenv.h>
-// #pragma STDC FENV_ACCESS ON
- 
-int main(void)
-{
-    printf("lgamma(10) = %f, log(9!) = %f\n", lgamma(10), log(2*3*4*5*6*7*8*9));
-    const double pi = acos(-1);
-    printf("lgamma(0.5) = %f, log(sqrt(pi)) = %f\n", log(sqrt(pi)), lgamma(0.5));
-    // special values
-    printf("lgamma(1) = %f\n", lgamma(1));
-    printf("lgamma(+Inf) = %f\n", lgamma(INFINITY));
- 
-    // error handling
-    errno = 0; feclearexcept(FE_ALL_EXCEPT);
-    printf("lgamma(0) = %f\n", lgamma(0));
-    if (errno == ERANGE)
-        perror("    errno == ERANGE");
-    if (fetestexcept(FE_DIVBYZERO))
-        puts("    FE_DIVBYZERO raised");
-}

Possible output:

-
lgamma(10) = 12.801827, log(9!) = 12.801827
-lgamma(0.5) = 0.572365, log(sqrt(pi)) = 0.572365
-lgamma(1) = 0.000000
-lgamma(+Inf) = inf
-lgamma(0) = inf
-    errno == ERANGE: Numerical result out of range
-    FE_DIVBYZERO raised

References

See also

- -
-
(C99)(C99)(C99)
 computes gamma function
(function)
C++ documentation for lgamma
- -
-Weisstein, Eric W. "Log Gamma Function." From MathWorld — A Wolfram Web Resource.
-

- © cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
- https://en.cppreference.com/w/c/numeric/math/lgamma -

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