#5520: [with patch; needs review] implement Pizer's algorithm for computing
Brandt
Modules and Brandt Matrices
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Reporter: was | Owner: craigcitro
Type: enhancement | Status: new
Priority: major | Milestone: sage-3.4.1
Component: modular forms | Keywords:
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Comment(by was):
Here is a way to trigger the problem mentioned above:
{{{
sage: n = 10000000; a = random_matrix(ZZ,4,x=-2^n,y=2^n).change_ring(QQ)
sage: b = a._multiply_pari(a)
*** the PARI stack overflows !
current stack size: 32000000 (30.518 Mbytes)
[hint] you can increase GP stack with allocatemem()
}}}
The easiest solution is probably just to just compute the height of a and
if it isn't "very big", then -- and only then -- use PARI:
{{{
sage: n = 10000000; a = random_matrix(ZZ,4,x=-2^n,y=2^n).change_ring(QQ)
sage: time h = a.height()
CPU times: user 0.01 s, sys: 0.00 s, total: 0.01 s
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5520#comment:10>
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