On Fri, Apr 24, 2009 at 10:52 AM, William Stein <wst...@gmail.com> wrote:
>
> Burcin and Mike -- Please read the below. There is an absolutely
> *MASSIVE* performance regression in pynac that Burcin surely caused.
>
> On Fri, Apr 24, 2009 at 10:35 AM, Ondrej Certik <ond...@certik.cz> wrote:
>>
>> Hi,
>>
>> I am puzzled by this:
>>
>> ond...@raven:~$ sage
>> ----------------------------------------------------------------------
>> | Sage Version 3.4.1, Release Date: 2009-04-21 |
>> | Type notebook() for the GUI, and license() for information. |
>> ----------------------------------------------------------------------
>> sage: var('x,y,z', ns=1)
>> (x, y, z)
>> sage: f = (x+y+z+1)^7
>> sage: time g = expand(f*(f+1))
>> CPU times: user 3.86 s, sys: 0.00 s, total: 3.86 s
>> Wall time: 3.86 s
>> sage:
>> Exiting SAGE (CPU time 0m3.90s, Wall time 0m26.84s).
>>
>>
>> ond...@raven:~$ sage
>> ----------------------------------------------------------------------
>> | Sage Version 3.4.1, Release Date: 2009-04-21 |
>> | Type notebook() for the GUI, and license() for information. |
>> ----------------------------------------------------------------------
>> sage: var('x,y,z')
>> (x, y, z)
>> sage: f = (x+y+z+1)^7
>> sage: time g = expand(f*(f+1))
>> CPU times: user 0.07 s, sys: 0.02 s, total: 0.09 s
>> Wall time: 1.23 s
>> sage:
>> Exiting SAGE (CPU time 0m0.12s, Wall time 0m9.59s).
>> Exiting spawned Maxima process.
>>
>> ond...@raven:~$ sage
>> ----------------------------------------------------------------------
>> | Sage Version 3.4.1, Release Date: 2009-04-21 |
>> | Type notebook() for the GUI, and license() for information. |
>> ----------------------------------------------------------------------
>> sage: from sympy import var, expand
>> sage: var('x,y,z')
>> (x, y, z)
>> sage: f = (x+y+z+1)^7
>> sage: time g = expand(f*(f+1))
>> CPU times: user 3.23 s, sys: 0.03 s, total: 3.26 s
>> Wall time: 3.27 s
>> sage:
>> Exiting SAGE (CPU time 0m3.36s, Wall time 0m30.75s).
>>
>>
>> What am I doing wrong? Even pure python sympy is faster than pynac...
>
> (1) You are not using sympy, for one:
I am pretty sure I am.
>
>> sage: var('x,y,z')
>> (x, y, z)
>
> Your var command doesn't inject x,y,z into the namespace!!
I am pretty sure it is:
sage: from sympy import var, expand
sage: var('x,y,z')
(x, y, z)
sage: type(x)
<class 'sympy.core.symbol.Symbol'>
>
> (2) I don't get the same times as you at all. I get pynac being 4
> times faster than Maxima and 5.56 times faster than Sympy on
> sage.math.
I might have screwed something up on my machine. I compiled from
source and I used the systemwide gfortran. Otherwise I did no other
changes.
>
> wst...@sage:~$ sage
> ----------------------------------------------------------------------
> | Sage Version 3.4.1, Release Date: 2009-04-21 |
> | Type notebook() for the GUI, and license() for information. |
> ----------------------------------------------------------------------
> sage: var('x,y,z', ns=1)
> (x, y, z)
> sage: f = (x+y+z+1)^7
> sage: time g=expand(f*(f+1))
> CPU times: user 0.74 s, sys: 0.00 s, total: 0.74 s
> Wall time: 0.75 s
> sage: var('x,y,z')
> (x, y, z)
> sage: f = (x+y+z+1)^7
> sage: time g=expand(f*(f+1))
> CPU times: user 0.09 s, sys: 0.01 s, total: 0.10 s
> Wall time: 3.04 s
> sage: from sympy import var, expand
> sage: x,y,z=var('x,y,z')
> sage: f = (x+y+z+1)^7
> sage: time g = expand(f*(f+1))
> CPU times: user 4.11 s, sys: 0.06 s, total: 4.17 s
> Wall time: 4.17 s
>
> These times are all pitiful compared to the time that Singular takes right
> now:
>
> sage: R.<x,y,z> = QQ[]
> sage: f = (x+y+z+1)^7
> sage: time g = f*(f+1) # also does "expand"
> CPU times: user 0.00 s, sys: 0.00 s, total: 0.00 s
> Wall time: 0.00 s
>
> There was clearly a *major* performance regression, because in Sage-3.2:
>
> wst...@sage:/disk/scratch/mabshoff-sage-releases/sage-3.2$ ./sage
> ----------------------------------------------------------------------
> | Sage Version 3.2, Release Date: 2008-11-20 |
> | Type notebook() for the GUI, and license() for information. |
> ----------------------------------------------------------------------
>
> sage: var('x,y,z',ns=1)
> (x, y, z)
> sage: f = (x+y+z+1)^7
> sage: time g=expand(f*(f+1))
> CPU times: user 0.05 s, sys: 0.00 s, total: 0.05 s
> Wall time: 0.05 s
>
> I knew something was messed up about symbolics when I tried mhansen's
> branch recently. Burcin, what did you do!?
Maybe something with numbers, or something else. In my experience it's
super easy to slow things down if one doesn't pay attention to it.
Ondrej
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