A little background first... I have been working on Mathics, <https://mathics.org/> a open-source implementation of the Wolfram Language.
Mathics relies heavily on sympy. For a little while I have been working on ensuring that Steve Skiena's Combinatorica <https://www.abebooks.com/servlet/BookDetailsPL?bi=30794099489&searchurl=isbn%3D0201509431%26sortby%3D17&cm_sp=snippet-_-srp1-_-title1> works on Mathics. In doing this, I was looking for a sympy equivalent to PartitionsP[] <https://reference.wolfram.com/language/ref/PartitionsP.html> . I couldn't find anything so initially I was generating all of the partitions using sympy.utilities.iterables.partitions and then taking the length. This is horribly inefficent. Therefore I thought, I'd use the algorition in Skiena's book which makes use of Euler's recurrence for the number of partitions. It took a little bit of tweaking to get it to be reasonably efficient in Python. The current impelemtation is here <https://github.com/mathics/Mathics/blob/master/mathics/builtin/combinatorial.py#L105-L136> . This might be of interest and use in sympy as well, so I'd like to mention it here. And if there is already such a routine in sympy, I'd would be grateful to know about. Thanks. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/86983b10-976c-4862-b959-367cd3772a4dn%40googlegroups.com.
