Interface expression conversion to gamma() and normalization

[rwst]

Pynac-0.7.4 provides functionality for conversion of factorial, binomial, and Pochhammer symbols to the resp. gamma expression. Also it provides gamma normalization, i.e., rewriting e.g. gamma(x-1) and gamma(x+2) within one expression to gamma(x-1) and (x-1)*x*(x+1)*gamma(x-1) and subsequent rational normalization, such that fractions can be canceled.

The ticket should add the Python interface and doctests.

Component: symbolics

Author: Ralf Stephan

Branch/Commit: 648e498

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/22174

[rwst]

Branch: u/rws/interface_expression_conversion_to_gamma___and_normalization

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

648e498

22174: Interface expression conversion to gamma() and normalization

[sagetrac-git]

Commit: 648e498

[rwst]

Author: Ralf Stephan

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

comment:4

LGTM.

[rwst]

comment:5

Thanks, this will speed up simplification as well (other ticket).

[vbraun]

Changed branch from u/rws/interface_expression_conversion_to_gamma___and_normalization to 648e498