Ticket #5109 (closed enhancement: fixed)

Opened 4 years ago

Last modified 4 years ago

[with patch, positive review] add support for Bell polynomials in Sage

Reported by: mhansen Owned by: mhansen
Priority: minor Milestone: sage-3.3
Component: combinatorics Keywords:
Cc: sage-combinat Work issues:
Report Upstream: Reviewers:
Authors: Merged in:
Dependencies: Stopgaps:

Description


Attachments

trac_5109.patch Download (2.7 KB) - added by mhansen 4 years ago.

Change History

comment:1 Changed 4 years ago by mhansen

  • Summary changed from add support for Bell polynomials in Sage to [with patch, needs review] add support for Bell polynomials in Sage

Changed 4 years ago by mhansen

comment:2 Changed 4 years ago by wdj

  • Summary changed from [with patch, needs review] add support for Bell polynomials in Sage to [with patch, positive review] add support for Bell polynomials in Sage

This applies cleanly to 3.3.alpha2 and passes sage -t. The examples also agree with some examples given on  http://en.wikipedia.org/wiki/Bell_polynomials, as well as this agreement: 

sage: stirling_number2(6,2) == bell_polynomial(6,2)(1,1,1,1,1) 
True
sage: stirling_number2(6,4) == bell_polynomial(6,4)(1,1,1) 
True
sage: stirling_number2(7,4) == bell_polynomial(7,4)(1,1,1,1) 
True

I ran sage -testall and got this failure: 

sage -t  "devel/sage/sage/rings/polynomial/toy_d_basis.py"  
**********************************************************************
File "/Volumes/G-DRIVE-MINI/sagestuff/sage-3.3.alpha2/devel/sage/sage/rings/polynomial/toy_d_basis.py", line 91:
    sage: d_basis(I)
Expected:
    [x + 170269749119, y + 2149906854, z + 735710619426, 282687803443]
Got:
    [x + 170269749119, y + 2149906854, z + 170335012540, 282687803443]
**********************************************************************

Though I don't know what a d_basis is, I think it is an unrelated failure so I'm giving this a positive review.

comment:3 Changed 4 years ago by wdj

One more test (also positive): 

sage: n=6
sage: add([bell_polynomial(n,i)((1,)*(n-i+1)) for i in range(1,n+1)]) == bell_number(n) 
True
sage: n = 7
sage: add([bell_polynomial(n,i)((1,)*(n-i+1)) for i in range(1,n+1)]) == bell_number(n) 
True
sage: n = 8
sage: add([bell_polynomial(n,i)((1,)*(n-i+1)) for i in range(1,n+1)]) == bell_number(n) 
True
sage: n = 20
sage: add([bell_polynomial(n,i)((1,)*(n-i+1)) for i in range(1,n+1)]) == bell_number(n) 
True
sage: bell_number(n)
51724158235372

Returns these pretty fast too!

comment:4 Changed 4 years ago by mabshoff

Note that partial credit goes to Blair - see

 http://groups.google.com/group/sage-devel/browse_thread/thread/4ae02fd827f68eed#

Cheers,

Michael

comment:5 Changed 4 years ago by mhansen

  • Status changed from new to assigned

Yep, I did the patch in his name.

comment:6 Changed 4 years ago by mabshoff

I got Blair's "real name" from the hg commit message, but I pinged him to see if he wants to be credited with that name or not.

Cheers,

Michael

comment:7 Changed 4 years ago by mabshoff

  • Status changed from assigned to closed
  • Resolution set to fixed

Merged in Sage 3.3.alpha3.

Cheers,

Michael

comment:8 Changed 4 years ago by nthiery

  • Cc sage-combinat added
Note: See TracTickets for help on using tickets.