Opened 3 years ago

Closed 3 years ago

#20428 closed defect (fixed)

crash with ultraspherical polynomials

Reported by: rws Owned by:
Priority: major Milestone: sage-duplicate/invalid/wontfix
Component: symbolics Keywords:
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: pynac-0.6.5 Stopgaps:

Description (last modified by rws)

%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.

Change History (4)

comment:1 Changed 3 years ago by rws

  • Dependencies set to pynac-0.6.5
  • Description modified (diff)

comment:2 Changed 3 years ago by rws

  • Milestone changed from sage-7.2 to sage-duplicate/invalid/wontfix
  • Status changed from new to needs_review

Fixed in #20312.

comment:3 Changed 3 years ago by rws

  • Status changed from needs_review to positive_review

comment:4 Changed 3 years ago by vbraun

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