First period resume

Here I present a brief resume of the work done in this first month.

1st week: Gammainc

The incomplete gamma function presented a series of inaccurate results in the previous implementation, so it has been decided to rewrite it from scratch. A big part of the work was done by Marco and Nir (here the discussion). I gave my contribution by fixing some problems in the implementation and by making a functioning commit (thanks to the suggestions given by Carne during the OctConf in Geneve).

2nd and 3rd week: Gammaincinv

The inverse of the incomplete gamma function was completely missing in Octave (and this was a problem of compatibility with Matlab). Now the function is present, written as a single .m file. The implementation consist in a simple, but efficient, Newton's method.

Last week: Betainc

When I first submitted my timeline, there was only a bug related to betainc, involving the input validation. During the first period of GSoC emerged a new bug of "incorrect result" type. From this, me and my mentor decided that it is necessary to rewrite the function, so I used this last week to study efficient algorithms to evaluate it. In particular, seems that the most efficient way is to use continude fractions, maybe after a rescale of the function. I'm already working on it, but I will complete it during the first week of august, after finishing the work on Bessel functions.