#14446: missing Sage interface for SymPy's RisingFactorial
------------------------------+------------------------
Reporter: zimmerma | Owner: was
Type: defect | Status: new
Priority: minor | Milestone: sage-6.4
Component: interfaces | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
------------------------------+------------------------
Old description:
> This is related to #14437:
> {{{
> sage: from sympy import Function, Symbol
> sage: u = Function('u')
> sage: n = Symbol('n', integer=True)
> sage: from sympy import rsolve
> sage: f = u(n+2) - u(n+1) + u(n)/4
> sage: rsolve(f,u(n))
> 2**(-n)*C0*RisingFactorial(C0/C1 + 1, n)/RisingFactorial(C0/C1, n)
> }}}
> The result returned by {{{rsolve}}} is a SymPy object:
> {{{
> sage: s = rsolve(f,u(n))
> sage: type(s)
> <class 'sympy.core.mul.Mul'>
> }}}
> Ideally, it should be automatically converted to Sage.
>
> However, if we try to convert it manually, we get:
> {{{
> sage: s._sage_()
> ---------------------------------------------------------------------------
> AttributeError Traceback (most recent call
> last)
>
> /users/caramel/zimmerma/svn/sagebook/tex/<ipython console> in <module>()
>
> /usr/local/sage-5.1-linux-64bit-ubuntu_12.04_lts-
> x86_64-Linux/local/lib/python2.7/site-packages/sympy/core/mul.py in
> _sage_(self)
> 1192 s = 1
> 1193 for x in self.args:
> -> 1194 s *= x._sage_()
> 1195 return s
> 1196
>
> /usr/local/sage-5.1-linux-64bit-ubuntu_12.04_lts-
> x86_64-Linux/local/lib/python2.7/site-packages/sympy/core/power.py in
> _sage_(self)
> 846
> 847 def _sage_(self):
> --> 848 return self.args[0]._sage_()**self.args[1]._sage_()
> 849
> 850 from add import Add
>
> AttributeError: 'RisingFactorial' object has no attribute '_sage_'
> }}}
> Paul
New description:
Minimal test case:
{{{
sage: import sympy
sage: SR(sympy.RisingFactorial(x,x))
AttributeError: 'RisingFactorial' object has no attribute '_sage_'
sage: SR(sympy.FallingFactorial(x,x))
AttributeError: 'FallingFactorial' object has no attribute '_sage_'
}}}
Original ticket description:
This is related to #14437:
{{{
sage: from sympy import Function, Symbol
sage: u = Function('u')
sage: n = Symbol('n', integer=True)
sage: from sympy import rsolve
sage: f = u(n+2) - u(n+1) + u(n)/4
sage: rsolve(f,u(n))
2**(-n)*C0*RisingFactorial(C0/C1 + 1, n)/RisingFactorial(C0/C1, n)
}}}
The result returned by {{{rsolve}}} is a SymPy object:
{{{
sage: s = rsolve(f,u(n))
sage: type(s)
<class 'sympy.core.mul.Mul'>
}}}
Ideally, it should be automatically converted to Sage.
However, if we try to convert it manually, we get:
{{{
sage: s._sage_()
---------------------------------------------------------------------------
AttributeError Traceback (most recent call
last)
/users/caramel/zimmerma/svn/sagebook/tex/<ipython console> in <module>()
/usr/local/sage-5.1-linux-64bit-ubuntu_12.04_lts-
x86_64-Linux/local/lib/python2.7/site-packages/sympy/core/mul.py in
_sage_(self)
1192 s = 1
1193 for x in self.args:
-> 1194 s *= x._sage_()
1195 return s
1196
/usr/local/sage-5.1-linux-64bit-ubuntu_12.04_lts-
x86_64-Linux/local/lib/python2.7/site-packages/sympy/core/power.py in
_sage_(self)
846
847 def _sage_(self):
--> 848 return self.args[0]._sage_()**self.args[1]._sage_()
849
850 from add import Add
AttributeError: 'RisingFactorial' object has no attribute '_sage_'
}}}
Paul
--
Comment (by rws):
This is now fixed in the proposed sympy pull request
https://github.com/sympy/sympy/pull/8592
but we will upload a branch with the specific sympy patch next.
--
Ticket URL: <http://trac.sagemath.org/ticket/14446#comment:8>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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