Sporadic errors in modform/ambient.py

[Jeroen Demeyer]

While testing sage-5.4, I discovered the following rare doctest error:

sage -t --long -force_lib devel/sage/sage/modular/modform/ambient.py
you are running out of primes. 1000 coprime primes
found**********************************************************************
File
"/release/buildbot/sage/sage-1/sage_upgrade_5.2/build/sage-5.5.beta0/devel/sage-main/sage/modular/modform/ambient.py",
line 815:
sage: [f[0]%p for p in prime_range(100)] # long time (0s, depends on
above)
Expected:
[0, 0, 0, 0, 1, 9, 2, 7, 0, 0, 0, 0, 1, 12, 9, 16, 37, 0, 21, 11,
70, 22, 0, 58, 76]
Got:
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1]
**********************************************************************
File
"/release/buildbot/sage/sage-1/sage_upgrade_5.2/build/sage-5.5.beta0/devel/sage-main/sage/modular/modform/ambient.py",
line 817:
sage: [f[42]%p for p in prime_range(100)] # long time (0s, depends
on above)
Expected:
[0, 0, 4, 0, 10, 4, 4, 8, 12, 1, 23, 13, 10, 27, 20, 13, 16, 59, 53,
41, 11, 13, 12, 6, 82]
Got:
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0]
**********************************************************************

I am going to bisect this, but it's non-trivial since the error is quite
rare. If anybody has any clues, that would help.

Jeroen.

[Volker Braun]

Just to state the obvious: "you are running out of primes. 1000 coprime primes found" doesn't sound good. Maybe thats where you are sporadically unlucky?

[Jeroen Demeyer]

On 2012-10-08 15:00, Jeroen Demeyer wrote:
> While testing sage-5.4, I discovered the following rare doctest error:
>
> sage -t --long -force_lib devel/sage/sage/modular/modform/ambient.py
> you are running out of primes. 1000 coprime primes
> found**********************************************************************

Just found out that the message "you are running out of primes" comes
from LinBox. So perhaps the LinBox upgrade (#12883) is to blame?