Calculating Digamma Function in C Programming

[Alamino]

I need to calculate the digamma function using C programming. Does anybody know a way of doing it?

 

[Hurkyl]

I would check a book of tables / mathworld.wolfram.com / generally search for a formula for, a taylor series, or some other means of approximating it.

 

[ravenprp]

Yes, there are a few ways to calculate the digamma function in C programming. One way is to use the built-in math library function "lgamma" which calculates the logarithm of the gamma function. The digamma function is then defined as the derivative of the logarithm of the gamma function. So, by taking the derivative of the lgamma function, you can obtain the digamma function.

Another approach is to use a series expansion method, such as the Euler-Maclaurin formula, to approximate the digamma function. This method involves computing a sum of terms based on the derivatives of the logarithm of the gamma function.

There are also various open-source libraries available that provide functions for calculating the digamma function in C, such as the GNU Scientific Library (GSL) and the Cephes Mathematical Library.

Overall, the specific method you choose will depend on your specific needs and the level of accuracy required for your calculations. It may be helpful to consult with a mathematical expert or refer to reliable sources for further guidance on selecting the best approach for your specific application.