#10133 closed defect (fixed)
Make sin(0), log(1) and similar expressions return Sage integers, not Python ints
Reported by:  kcrisman  Owned by:  burcin 

Priority:  major  Milestone:  sage6.4 
Component:  symbolics  Keywords:  type coercion symbolic 
Cc:  eviatarbach  Merged in:  
Authors:  Jeroen Demeyer  Reviewers:  Ralf Stephan 
Report Upstream:  N/A  Work issues:  
Branch:  c8c26e1 (Commits, GitHub, GitLab)  Commit:  
Dependencies:  #17130  Stopgaps: 
Description (last modified by )
From this thread:
> > sage: type(log(1)) > > <type 'int'> > > sage: log(1).n() > >  > > AttributeError: 'int' object has no attribute 'n' > > sage: Integer(log(1)).n() > > 0.000000000000000 > > sage: a = Integer(1) > > sage: a.log() > > 0 > > sage: type(a.log()) > > <type 'int'> > > sage: from sage.functions.log import function_log > > sage: function_log(Integer(1)) > > 0 > > sage: type(function_log(Integer(1))) > > <type 'int'> > > > Is there any way to get around this in the code, or are we pretty much > > stuck with this because of how GinacFunctions work? I'm not 100% sure > > this is a bug in log; maybe instead we should extend int so that > > This is a bug in the log() function, and any other function which > returns exact values like 0 or 1. We already work around most cases, > see lines 720722 and 736761 of sage/symbolic/function.pyx. > > The correct fix is to change the corresponding pynac functions to > coerce the exact value to the parent of the argument before returning > it. For example, all the lines "return _ex1;" or "return _ex0;" in > > http://pynac.sagemath.org/hg/file/b233d9dadcfa/ginac/inifcns_trans.cpp > > has to be changed this way. > Yup, I see what you are talking about  e.g. if (x.is_equal(_ex1)) // log(1) > 0 return _ex0; Although it might be nice to stay relatively close to Ginac and fix such things on the Sage level if that's not really bad.
This ticket's goal is to implement one of these solutions (that is, catch this in function.pyx or in Pynac).
We might as well also deal with sin(0), tan(0), sin(pi)
from #10972 here as well, otherwise that really wasn't a duplicate.
Change History (18)
comment:1 Changed 11 years ago by
comment:2 Changed 10 years ago by
ping. I just noticed this in a different context.
comment:3 Changed 10 years ago by
 Description modified (diff)
comment:4 Changed 10 years ago by
See also this sagedevel thread.
comment:5 Changed 10 years ago by
 Keywords type coercion symbolic added
 Summary changed from Make sure log(1) returns an Integer, not an int to Make sin(0), log(1), cos(0), and similar expressions return Sage integers, not symbolic expressions or Python ints
See also this sagedevel thread, where it seems that the consensus is that such things should give Sage Integer
s, though at #10972 Burcin seems to suggest that symbolic expressions are appropriate.
comment:6 Changed 9 years ago by
 Milestone changed from sage5.11 to sage5.12
comment:7 Changed 9 years ago by
 Cc eviatarbach added
comment:8 Changed 9 years ago by
 Milestone changed from sage6.1 to sage6.2
comment:9 Changed 8 years ago by
 Milestone changed from sage6.2 to sage6.3
comment:10 Changed 8 years ago by
 Milestone changed from sage6.3 to sage6.4
comment:11 Changed 8 years ago by
 Dependencies set to #17130
comment:12 Changed 8 years ago by
 Branch set to u/jdemeyer/ticket/10133
 Modified changed from 11/26/14 16:17:23 to 11/26/14 16:17:23
comment:13 Changed 8 years ago by
 Commit set to c8c26e1ca6195841b5bd1bb900a33eef3bb30b60
 Status changed from new to needs_review
New commits:
6d10729  Simplify numerical evaluation of BuiltinFunctions

b6e1ed4  Merge remotetracking branches 'origin/u/jdemeyer/ticket/17131' and 'origin/u/jdemeyer/ticket/17133' into ticket/17130

382f97a  Merge branch 'u/jdemeyer/ticket/17130' of trac.sagemath.org:sage into 6.5beta1

7265989  17130: reviewer's patch: fix typo

c47dbd4  Fix Trac #17328 again in a better way

a486db2  Call the factorial() method of an Integer

c8c26e1  Convert Ginac function results to the correct parent

comment:14 Changed 8 years ago by
 Summary changed from Make sin(0), log(1), cos(0), and similar expressions return Sage integers, not symbolic expressions or Python ints to Make sin(0), log(1) and similar expressions return Sage integers, not Python ints
comment:15 Changed 8 years ago by
 Reviewers set to Ralf Stephan
 Status changed from needs_review to positive_review
Looks good and passes make ptestlong
.
comment:16 Changed 8 years ago by
 Branch changed from u/jdemeyer/ticket/10133 to c8c26e1ca6195841b5bd1bb900a33eef3bb30b60
 Resolution set to fixed
 Status changed from positive_review to closed
comment:17 Changed 7 years ago by
 Commit c8c26e1ca6195841b5bd1bb900a33eef3bb30b60 deleted
Actually this should have been fixed in Pynac. Now, accidentally the recent patches dealing with https://github.com/pynac/pynac/issues/7 automatically produce this behaviour. Which will be Pynac0.4.4. The wrapper from this ticket should then be removed.
comment:18 Changed 7 years ago by
 Description modified (diff)
#10972 was closed as a duplicate. Ironic that I reported both, though in my defense, that ticket does list a few specific functions beyond log for which that happens, and it was 8 months ago :)