log_gamma

Evaluates the logarithm of the absolute value of the gamma function log ∣Γ(x)∣.

Synopsis

#include <imsl.h>

float imsl_f_log_gamma (float x)

The type double function is imsl_d_log_gamma.

Required Arguments

float x (Input)
Point at which the logarithm of the absolute value of the gamma function is to be evaluated.

Return Value

The value of the logarithm of gamma function, log ∣Γ(x)∣.

Description

The logarithm of the absolute value of the gamma function log ∣Γ(x)∣ is computed.

 

Figure 1,  Plot of log ∣Γ(x)∣

Example

In this example, log ∣Γ(3.5)∣ is computed and printed.

 

#include <stdio.h>

#include <imsl.h>

 

int main()

{

float x = 3.5;

float ans;

 

ans = imsl_f_log_gamma(x);

printf("log gamma(%f) = %f\n", x, ans);

}

Output

 

log gamma(3.500000) = 1.200974

Warning Errors

IMSL_NEAR_NEG_INT_WARN

The result is accurate to less than one-half precision because x is too close to a negative integer.

Fatal Errors

IMSL_NEGATIVE_INTEGER	The argument for the function cannot be a negative integer.
IMSL_NEAR_NEG_INT_FATAL	The argument for the function is too close to a negative integer.
IMSL_LARGE_ABS_ARG_OVERFLOW	|x| must not be so large that the result overflows.