Mathematica 9 is now available
Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2010

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Manually nested Tables faster than builtin

  • To: mathgroup at smc.vnet.net
  • Subject: [mg113473] Re: Manually nested Tables faster than builtin
  • From: eric g <eric.phys at gmail.com>
  • Date: Sat, 30 Oct 2010 04:37:26 -0400 (EDT)

I get: 3.83642 and 23.6414
version 7 in:
two AMD Athlon 64 4400+


On 10/29/2010 03:30 AM, Tomas Garza wrote:
> No, I don't have a clue. First of all, I'm surprised the my PC takes so much longer than yours. I have Windows Vista 64 bit, and Intel(R) Core(TM)2 Duo CPU     P8400  @ 2.26GHz with 4.00 GB, which doesn't seem to differ all that much from yours.
> And then, if you look at FullForm in both cases (for small values of imax and jmax) the results are identical (?)
> -Tomas
>
>    
>> Date: Thu, 28 Oct 2010 04:28:18 -0400
>> From: sschmitt at physi.uni-heidelberg.de
>> Subject:  Re: Manually nested Tables faster than builtin nesting?
>> To: mathgroup at smc.vnet.net
>>
>> Hi Tomas!
>>
>> With "manually" I mean
>>
>> "Table[Table[..., {i, imax}], {j, jmax}]"
>>
>> (two Tables explicitly/manually)
>>
>> instead of
>>
>> "Table[..., {i, imax}, {j, jmax}]"
>>
>> (one Table but two iterators).
>>
>> Can you explain the difference in speed?
>>
>> Cheers,
>>
>> Sebastian
>>
>> PS:
>>
>> $Version
>> "7.0 for Linux x86 (64-bit) (February 18, 2009)"
>>
>> $ grep "model name" /proc/cpuinfo
>>
>> model name      : Intel(R) Core(TM)2 Duo CPU     P8600  @ 2.40GHz
>> model name      : Intel(R) Core(TM)2 Duo CPU     P8600  @ 2.40GHz
>>
>> Tomas Garza wrote:
>>      
>>> You must have a very fast machine! Any way, I get 5.647 and 43.134, respectively. The factor in both machines is close to 8, not 2 (what do you mean manually?)
>>>
>>> -Tomas
>>>
>>>        
>>>> Date: Wed, 27 Oct 2010 05:13:59 -0400
>>>> From: sschmitt at physi.uni-heidelberg.de
>>>> Subject:  Manually nested Tables faster than builtin nesting?
>>>> To: mathgroup at smc.vnet.net
>>>>
>>>> Dear all!
>>>>
>>>> I find that manually nested Tables are faster (factor 2 in my example)
>>>> compared to the builtin nesting. I probably do a stupid thinko. Could
>>>> you please have a look?
>>>>
>>>> In[52]:== imax == jmax == 5000;
>>>>
>>>> In[53]:== (tabletable == Table[Table[i*j, {i, imax}], {j, jmax}];) //
>>>>    Timing // First
>>>>
>>>> Out[53]== 1.84
>>>>
>>>> In[54]:== (table == Table[i*j, {i, imax}, {j, jmax}];) // Timing // Fi=
>>>>          
> rst
>    
>>>> Out[54]== 14.55
>>>>
>>>> In[55]:== tabletable ==== table
>>>>
>>>> Out[55]== True
>>>>
>>>> Thanks,
>>>>
>>>> Sebastian
>>>>
>>>>          
>>>   		 	   		
>>>        
>>
>>      
>   		 	   		
>    



  • Prev by Date: Re: Determining the root of the characteristic equation
  • Next by Date: Re: Sneaky white space (binary search)
  • Previous by thread: Re: Manually nested Tables faster than builtin
  • Next by thread: How to see command itself but not the result