ASA147
the Incomplete Gamma Function

ASA147 is a C++ program, using double precision arithmetic, which evaluates the incomplete Gamma function.

ASA147 is Applied Statistics Algorithm 147. Source code for many Applied Statistics Algorithms is available through STATLIB.

Related Data and Programs:

ASA032 is a C++ library which evaluates the incomplete Gamma function.

ASA147 is also available in a FORTRAN77 version and a FORTRAN90 version and a MATLAB version.

ASA239 is a C++ library which evaluates the incomplete Gamma function.

DCDFLIB is a C++ library which evaluates and inverts a number of statistical distributions.

GSL is a C++ library which includes many routines for evaluating probability distributions.

PROB is a FORTRAN90 library which evaluates and inverts a number of probabilistic distributions.

TEST_VALUES is a C++ library which contains sample values for a number of distributions.

TOMS435 is a FORTRAN90 library which evaluates the modified incomplete Gamma function.

TOMS708 a FORTRAN90 library which includes routines to evaluate the incomplete Gamma function.

Reference:

1. Chi Leung Lau,
   Algorithm AS 147: A Simple Series for the Incomplete Gamma Integral,
   Applied Statistics,
   Volume 29, Number 1, 1980, pages 113-114.

Source Code:

• asa147.C, the source code.
• asa147.H, the include file.
• asa147.csh, commands to compile the source code.

Examples and Tests:

• asa147_prb.C, a sample calling program.
• asa147_prb.csh, commands to compile and run the sample program.
• asa147_prb_output.txt, the output file.

List of Routines:

• ALNGAM computes the logarithm of the gamma function.
• GAMMA_INC_VALUES returns some values of the incomplete Gamma function.
• GAMMDS computes the incomplete Gamma integral.
• TIMESTAMP prints out the current YMDHMS date as a timestamp.

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