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Re: Slow Show/Graphics in v6.0

  • To: mathgroup at smc.vnet.net
  • Subject: [mg80965] Re: [mg80906] Slow Show/Graphics in v6.0
  • From: Alex Shvydky <ashv at lle.rochester.edu>
  • Date: Thu, 6 Sep 2007 05:33:36 -0400 (EDT)
  • References: <200709050653.CAA26889@smc.vnet.net> <200709050938.50140.cfo@lanl.gov>

Thanks Curtis for the input!
We ran the test on another computer with Mathematica 5.2
(4core Opteron with some ATI 9600 or so graphics card) and interestingly
it took about 2 seconds i.e. not significantly faster
than on mine with the Intel's built-in-the-chipset graphics.

We should repeat the tests with Mathematica 6.0 on that other computer.

Alex

Curtis Osterhoudt wrote:
> Hi, Alex, 
>
>    I just tried the second example on a newish computer with a medium-end 
> graphics card....
>
>    The actual calculation's timing was reported as ~0.89 seconds, but the 
> display of the graphics took at least 40 seconds, and any resizing of the 
> graphic drags one processor to a halt. 
>
>     I specifically got this computer (and graphics card) to run Mathematica 
> quickly. Most of the calculations I've done with it benefit GREATLY from the 
> graphics card, so that's probably one's best bet to radically speed up many 
> operations if plotting of any sort is involved.
>
>
>
> On Wednesday 05 September 2007 00:53:32 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?).
>>
>>
>> Thanks,
>> Alex Shvydky
>>     
>
>
>
>   

-- 
_______________________________________________________________

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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