Factorial method has an incorrect method signature about big-math HOT 7 CLOSED

Thanks for the info.

I have corrected the README.

Adding the gamma function is a good idea.
I would rather make it a separate function gamma(BigDecimal, MathContext) and leave the factorial(int) function as it is.

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Or adding an overloaded variant:
factorial(BigDecimal, MathContext)

from big-math.

The overload would definitely be a good idea. Leaving the factorial(int) function in place alongside an overload would prevent existing programs from breaking with the addition.

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Implementing gamma() is definitely not trivial.

Euler's infinite product definition
https://en.wikipedia.org/wiki/Gamma_function#Euler's_definition_as_an_infinite_product
is easy to implement but after a 1000 multiplications achieves only 3 digits precision for factorial(3.0).
This will not work.

Some numerical calculation variants explained:
http://www.rskey.org/CMS/index.php/the-library/11

This one looks promising:
http://www.vttoth.com/CMS/projects/41

Best algorithm sofar:
https://en.wikipedia.org/wiki/Spouge%27s_approximation

If nobody comes up with a working implementation in the meantime I will first finish release 2.0 (introducing BigComplex) before I attack gamma()

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Wrote a little blog describing the development of this issue, since it is quite an interesting case.

https://github.com/eobermuhlner/big-math/blob/master/docs/markdown/gamma/gamma.md

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I looked through your article, didn't realize the gamma function would be this much of a burden to implement. Thanks for your work on this issue!

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The effort was pretty typical for a new function.

And it is fun 😄

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