#20428: crash with ultraspherical polynomials
-------------------------------+------------------------
Reporter: rws | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-7.2
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: pynac-0.6.5 | Stopgaps:
-------------------------------+------------------------
Changes (by rws):
* dependencies: => pynac-0.6.5
Old description:
> {{{
> %time _=ultraspherical(10000,7/5,x)
> ...
> RuntimeError: ECL says: Memory limit reached. Please jump to an outer
> pointer, quit program and enlarge the
> memory limits before executing the program again.
> }}}
>
> Currently Maxima is called with ultraspherical (Gegenbauer) polynomials
> but already a naive Python implementation is faster:
> {{{
> sage: def u(n,a):
> return sum((-1)^k*prod(i for i in srange(a,
> n-k+a))/factorial(n-2*k)/factorial(k)*(2*x)^(n-2*k) for k in
> range(floor(n/2)+1))
> ....:
> sage: %time _=u(10000,7/5)
> CPU times: user 1min 43s, sys: 128 ms, total: 1min 43s
> Wall time: 1min 43s
> }}}
> and the Maxima version would be not even expanded. A direct Pynac
> implementation should need only seconds.
New description:
{{{
%time _=ultraspherical(10000,7/5,x)
...
RuntimeError: ECL says: Memory limit reached. Please jump to an outer
pointer, quit program and enlarge the
memory limits before executing the program again.
}}}
Currently Maxima is called with ultraspherical (Gegenbauer) polynomials
but already a naive Python implementation is faster:
{{{
sage: def u(n,a):
return sum((-1)^k*prod(i for i in srange(a,
n-k+a))/factorial(n-2*k)/factorial(k)*(2*x)^(n-2*k) for k in
range(floor(n/2)+1))
....:
sage: %time _=u(10000,7/5)
CPU times: user 1min 43s, sys: 128 ms, total: 1min 43s
Wall time: 1min 43s
}}}
and the Maxima version would be not even expanded. A direct Pynac
implementation needs 25 seconds.
--
--
Ticket URL: <http://trac.sagemath.org/ticket/20428#comment:1>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at https://groups.google.com/group/sage-trac.
For more options, visit https://groups.google.com/d/optout.
