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  * [[http://www.unk.edu/uploadedFiles/facstaff/profiles/willisb/solve-talk(3).pdf|Talk by Barton Willis]] on Maxima's to_poly solve function
  * [[http://maxima.cvs.sourceforge.net/viewvc/maxima/maxima/share/contrib/rtest_to_poly_solver.mac?view=markup|test suite]] for Maxima's to_poly solver

Symbolics in Sage

These pages are aimed at developers of symbolics functionality in Sage. If you're interested in helping out with any of the items below please contact the sage-devel googlegroup or the people already working on your item of interest.

Pynac and Maxima based symbolics

Most symbolics functionality in Sage relies on Maxima. While Maxima is a very mature and capable software package, there are some problems with using it in Sage. Namely,

  • the pexpect interface to Maxima is slow, and
  • Sage developers cannot fix problems in Maxima or enhance its functionality.

To provide a better framework for symbolics in Sage, and to make implementation of new symbolics functionality that relies on components of Sage easier; we created a fork of the C++ library GiNaC, called Pynac, which works with Python types. There are still some low level changes required in Pynac before it can be used as a basis for symbolics in Sage, we keep track of these at the Pynac todo list.

With the switch to Pynac based symbolics, it will be possible to implement native functionality in Sage. Here is a brief list of areas that need work.

TODO

Some of the functionality listed above is provided by Maxima wrappers at the moment.

  • Summation
  • Hypergeometric functions
    • HYP from Christian Krattenthaler for MMA

    • HYPERG from Bruno Gauthier for Maple

      • This should let us do the following:

        $$ \sum_{s \ge m} \binom{s}{m} \frac{(n)_s}{(\frac{n}{2} + 1)_s 2{s}} = \frac{(n)_m}{2{

m}(\frac{n}{2}+1)_m} \,_2 F_1 \left( \begin{array}{cc} m+1, m+n \\ m+ \frac{n}{2} +1 \end{array} ; \frac{1}{2} \right) = \frac{2^{n-1} \Gamma(\frac{n}{2} +1) \Gamma(\frac{m}{2} + \frac{n}{2})}{\Gamma(\frac{m}{2} + 1)\Gamma(n)}$$

  • Meijer G-Functions
  • Generating functions
    • This is a building block for many things. A prerequisite for this is linear algebra over polynomial rings, Burcin Erocal is working on this.
    • gfun by Bruno Salvy and Paul Zimmermann included in Maple

    • GeneratingFunctions by Christian Mallinger for MMA

symbolics (last edited 2017-05-15 19:43:59 by chapoton)