### Highlights from Gamma

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# Gamma

### Paul Godfrey (view profile)

06 Jun 2003 (Updated )

Compute a very accurate Gamma function over the entire complex plane.

File Information
Description

A very accurate complex Gamma function valid over the entire complex plane. This function is more accurate than MATLAB's own real only Gamma function.

Acknowledgements

This file inspired Variable Order Derivatives.

MATLAB release MATLAB 6.0 (R12)
21 Aug 2015 Karan Gill

### Karan Gill (view profile)

Also worth mentioning that if you have the Symbolic Math Toolbox, you calculate the complex gamma function in double using it. Example:

>> double(gamma(sym(1+1i)))
ans =
0.4980 - 0.1549i

Comment only
24 Feb 2015 G. Merchant

### G. Merchant (view profile)

Loss of accuracy in complex plane:

Using this routine:
gamma(-2-2e-7 i)=0.462366678321968 + 2499999.99999981i

Using backwards recursion:
gamma(0-2e-7 i)=-0.577215664901504 + 4999999.99999981i
gamma(-1-2e-7i)=gamma(-2e-7i)/(-1-2e-7i) =-0.577215664901504 + 4999999.99999981i
gamma(-2-2e-7i)=gamma(-1-2e-7i)/(-2-2e-7i)=0.461392167549202 + 2499999.99999982i

Note that the real part agree for only 2 digits. The second calculation based on backwards recursion agrees Mathematica and Fortran. Look for discussion on Google Groups by Krishna Myneni.
Is it possible to fix this issue?

Comment only
23 May 2012 Marzieh

### Marzieh (view profile)

28 Oct 2011 Jacques Burrus

### Jacques Burrus (view profile)

Thank you!

05 Jun 2009 Slimane Grine

### Slimane Grine (view profile)

Thanks. Very useful!

18 Jan 2009 Deepak

### Deepak (view profile)

Its so lovely to see this function on the first search.
Extremely handy.
Please post some references as well for the theory.

10 Apr 2006 Matteo Borghi
22 Mar 2006 Rudi Fruehwirth

Very useful!

31 Jan 2006 Bill Davidson

Thank you. Excellent. It is a handy function to have around.

09 Nov 2005 hugues de chatellus