Hi,
Here is a short example to replicate the first error mentioned below:
b = [var('b_%s'%i) for i in range(4)]
precomp = (2^b_2 + 2)*(2^b_1 + 2^(-b_1) + 2^b_1*2^b_0 - 2^b_1*2^(-b_0)
- 2^(-b_1)*2^b_0 - 2^(-b_1)*2^(-b_0) + 2^b_0 + 2^(-b_0) - 9) + (2^b_1 +
2^(-b_1) + 2^b_1*2^b_0 - 2^b_1*2^(-b_0) - 2^(-b_1)*2^b_0 -
2^(-b_1)*2^(-b_0) + 2^b_0 + 2^(-b_0) - 9)/2^b_2
repl_dict = {b_0: b_0, b_3: b_1, b_2: b_3, b_1: b_2}
P = precomp.substitute(repl_dict)
P.expand()
I will take a break now. I'd appreciate any help tracking down the
problem (in pynac) if anybody has the time.
Cheers,
Burcin
On Wed, 1 Sep 2010 08:25:07 -0700 (PDT)
Jean-Pierre Flori <jpfl...@gmail.com> wrote:
> Hello,
>
> I'm using Sage to do some symbolic computations.
> What I am basically trying to do is to compute sums made of terms of
> the form :
> cst_{i_0,...,i_d)*b_0^{i_0}*...*b_d^{i_d}*2^{-b_0-...-b_d}
> where the b_i are variables
> (i.e. a product of an exponential with b_i in the exponent by a
> multivariate polynomial in b_i)
> using functions (especially symbolic_sum) from sage.calculus.calculus.
> I am regularly calling expand() and simplify() functions as well as
> some custom functions using substitute() to get a more compact
> expression and avoid redundant terms.
> Everything works fine as long as the sums are not too "complicated",
> but Sage segfaults when they become too big.
> Running Sage with the -gdb flag, gives different errors according to
> which of my functions I am calling, but both errors seem to be related
> to a "compare" function in Pynac (SIGSEGV or SIGBUS):
>
> First error message :
> Program received signal SIGSEGV, Segmentation fault.
> GiNaC::power::compare (this=0x3281c20, other=...) at power.cpp:899
> 899 power.cpp: Aucun fichier ou dossier de ce type.
> in power.cpp
>
> Second error message :
> Program received signal SIGBUS, Bus error.
> GiNaC::mul::compare (this=0x83490e0, other=...) at mul.cpp:1174
> 1174 mul.cpp: Aucun fichier ou dossier de ce type.
> in mul.cpp
>
>
> My box is running a Debian unstable with packages from the
> experimental repository.
> My kernel version is 2.6.35, compiled by myself.
> My cpu is a Intel(R) Core(TM)2 Quad CPU Q6600.
> The error is happening with Sage 4.5.2 and 4.4.4.
> I compiled both of them myself with gcc (Debian 4.4.4-11) 4.4.5
> 20100824 (prerelease).
> I also tried the precompiled sage-4.5.2-linux-64bit-ubuntu_10.04_lts-
> x86_64-Linux which gives me the same result.
>
> I didn't manage to reproduce the bug with a short and simple piece of
> code.
> However I can mail the source code and instructions to reproduce the
> bug to anyone who can help.
> I will also provide any information needed to investigate this
> problem.
> I am currently trying to compile Sage on another box to do another
> test.
> Any help will be appreciated, and thanks for a such a great piece of
> software.
>
> Best regards,
>
> Jean-Pierre Flori
>
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