Comments (7)
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.
from big-math.
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.
from big-math.
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()
from big-math.
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
from big-math.
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!
from big-math.
The effort was pretty typical for a new function.
And it is fun 😄
from big-math.
Related Issues (20)
- Prepare release 2.2.1
- Support temporary local MathContext in DefaultBigDecimalMath
- Prepare release 2.3.0
- root(x, n) with large n is very slow
- Prepare release 2.3.1 HOT 2
- sqrt hangs HOT 1
- sqrt rounding HOT 2
- BigRational toFloat() can fail in a slightly unexpected way HOT 4
- `BigRational.toIntegerRationalString()` with small negative numbers
- Issue with larger scales? HOT 3
- Questions about the big-math library: Capabilities and Future. HOT 12
- Something the matter with the 2.3.1 release? HOT 1
- Prepare release 2.3.2
- Question about big-math .jar file. HOT 1
- Performance issue in BigDecimalMath.pow() HOT 1
- BigComplexMath.sqrt fails on non-positive real numbers HOT 2
- Use BigDecimal.compareTo() insted of BigDecimal.equals()
- Pow throws Overflow in special case
- doubleValue performance
- BigComplexMath#sqrt fails when x is a negative real number
Recommend Projects
-
React
A declarative, efficient, and flexible JavaScript library for building user interfaces.
-
Vue.js
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
-
Typescript
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
-
TensorFlow
An Open Source Machine Learning Framework for Everyone
-
Django
The Web framework for perfectionists with deadlines.
-
Laravel
A PHP framework for web artisans
-
D3
Bring data to life with SVG, Canvas and HTML. 📊📈🎉
-
Recommend Topics
-
javascript
JavaScript (JS) is a lightweight interpreted programming language with first-class functions.
-
web
Some thing interesting about web. New door for the world.
-
server
A server is a program made to process requests and deliver data to clients.
-
Machine learning
Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.
-
Visualization
Some thing interesting about visualization, use data art
-
Game
Some thing interesting about game, make everyone happy.
Recommend Org
-
Facebook
We are working to build community through open source technology. NB: members must have two-factor auth.
-
Microsoft
Open source projects and samples from Microsoft.
-
Google
Google ❤️ Open Source for everyone.
-
Alibaba
Alibaba Open Source for everyone
-
D3
Data-Driven Documents codes.
-
Tencent
China tencent open source team.
from big-math.