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MathGroup Archive 2007

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Re: Slow Show/Graphics in v6.0

  • To: mathgroup at smc.vnet.net
  • Subject: [mg80962] Re: [mg80906] Slow Show/Graphics in v6.0
  • From: Alex Shvydky <ashv at lle.rochester.edu>
  • Date: Thu, 6 Sep 2007 05:32:04 -0400 (EDT)
  • References: <200709050653.CAA26889@smc.vnet.net> <8860260B-096B-4F56-95A1-E2208C4BE319@wolfram.com>

Hello Brett,
Thanks for the reply.
Do I understand it correctly that you confirm that the new
Mathematica v6.0 is upto 100 slower on sertain types
of operations compared to v5.0???

Is this a design issue or a simple future patch can fix it?

At this point v6.0 is completely unusable for my applications.
It is like you would buy a new car that would offer more
features and comfort and look fabulous but would have
5 miles per hour maximum speed.

You guys should do a better job at this.
Alex

Brett Champion wrote:
> On Sep 5, 2007, at 1:53 AM , Alex Shvydky wrote:
>
>> Hello,
>>
>> Just wanted to share my puzzlement (utter disappointment/
>> frastration) with a ridiculously slow speed of Show/Graphics
>> routines in the v6.0 of Mathematica as compared to 5.2,
>> which to me at this point makes v6.0 plain unusable.
>>
>> Working with hydrodynamic simulations I need to
>> visualize the computational grid. So I wrote
>> simple Mathematica routines to draw a simulation grid.
>> In 5.2 they worked fabulously for the past couple of
>> years.
>>
>> Here's an example.
>> First, set up two 2dimensional x- and y-coordinate
>> arrays.
>>
>> Timing[
>>    mr = 350;
>>    mt = 350;
>>    xar = Table[((ir - 1.)/(mr - 1.))*Cos[Pi*((it - 1.)/(mt - 1.))],
>>                {it, 1, mt}, {ir, 1, mr}];
>>    yar = Table[((ir - 1.)/(mr - 1.))*Sin[Pi*((it - 1.)/(mt - 1.))],
>>                {it, 1, mt}, {ir, 1, mr}];
>> ]
>>
>> In v6.0 it took
>> Out[3]= {2.312, Null}
>> In v5.2 it took
>> {0.281 Second, Null}
>>
>> Which is an order of magnitude difference, but hold on.
>> Now let's plot the mesh by simply constructing table
>> of edges of all the cells (I am aware that the algorithm
>> below is very unoptimized and can be made faster etc. etc.
>> It was not my intention to discuss here what should be the
>> fastest algorithm to plot a 2-d mesh,
>> nor was it my intention to debate the issue why one
>> would need to plot such a large mesh in the first place...,
>> but rather to compare the execution time for an IDENTICAL
>> code on v6.0 and v5.2. and get some confirmation/explanation
>> of such a suspiciously slow execution speed!).:
>>
>> Timing[
>> Show[
>>     Graphics[{Hue[0.7], AbsoluteThickness[0.1],
>>     Table[{Line[{{xar[[it,ir]], yar[[it,ir]]},
>>                       {xar[[it,ir + 1]],yar[[it,ir + 1]]},
>>                       {xar[[it + 1,ir + 1]], yar[[it + 1,ir + 1]]},
>>                       {xar[[it + 1,ir]], yar[[it + 1,ir]]}}]},
>>          {ir, 1, mr - 1}, {it, 1, mt - 1}]
>>     }],
>> PlotRange -> {{-1, 1}, {0, 1}}, AspectRatio -> 1/2, Axes -> True,
>> DisplayFunction -> $DisplayFunction, ImageSize -> 800]]
>>
>> While the timing as, it is returned by the Timing[] function,
>> is smaller in the v6.0:
>> {1.703, <Here goes the actual graphics>}
>> vs.
>> {2.094 Second, -Graphics-}
>> in v5.2
>>
>>
>> The actual cell evaluation time in v.6.0 is 124.11 seconds
>> vs. 2.22 seconds in v 5.2. ???!!!!!!!
>>
>> Could anybody please confirm this. Also it would be helpful
>> if someone from Wolfram Research would explain if
>> that is intended (unavoidable) by design or maybe
>> a simple setting (which I am unaware of) or a future patch
>> will be able to fix it.
>>
>> Also, it is horribly slow to resize the above graphics
>> in v5.2 you just grab the corned and drag. In v6.0 you
>> must do it 10-100 times slower (is it possible
>> that I just have a very poor graphics card?).
> This should be much faster to render, although it's still a bit 
> sluggish to resize.
>
>
> Timing[Show[
>   Graphics[{Hue[0.7],
>     AbsoluteThickness[
>      0.1], {Line[
>       Developer`ToPackedArray[
>        N[Flatten[
>          Table[{{xar[[it, ir]], yar[[it, ir]]}, {xar[[it, ir + 1]],
>             yar[[it, ir + 1]]}, {xar[[it + 1, ir + 1]],
>             yar[[it + 1, ir + 1]]}, {xar[[it + 1, ir]],
>             yar[[it + 1, ir]]}}, {ir, 1, mr - 1}, {it, 1, mt - 1}], 
> 1]]]]}}],
>   PlotRange -> {{-1, 1}, {0, 1}}, AspectRatio -> 1/2, Axes -> True,
>   DisplayFunction -> $DisplayFunction, ImageSize -> 800]]
>
> Brett Champion
> Wolfram Research
>

-- 
_______________________________________________________________

Alex Shvydky                           <ashv at lle.rochester.edu>

Research Associate
Computational Design Group

Laboratory for Laser Energetics        Office:  1423 COI
University of Rochester                Phone:  (585) 275-9539
250 East River Road                    FAX:    (585) 275-5960
Rochester NY  14623
_______________________________________________________________



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