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Re: Curious Timing Results

• To: mathgroup at smc.vnet.net
• Subject: [mg38717] Re: Curious Timing Results
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Mon, 6 Jan 2003 03:45:09 -0500 (EST)
• Organization: Universitaet Leipzig
• References: <av36rc$g08$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Hi,

In[]:=Developer`PackedArrayQ /@ {x, y}

Out[]={True,False}

Some times PackedArrays are slower -- you have found one.
I expect, that the x Array must be unpacked and this cause
the longer time in Inner[Divide,x,x]

Regards
  Jens

Chris Grant wrote:
> 
> I find the Timing results below a little curious.  Is there a simple
> explanation why I shouldn't?
> 
> Chris Grant
> 
> In[1]:=  x = Table[2.,{i,100000}];
> 
> In[2]:=  y = Table[If[i<1000000,2.,i],{i,100000}];
> 
> In[3]:=  SameQ[x,y]
> 
> Out[3]=  True
> 
> In[4]:=  Timing[Inner[Divide,x,x]]
> 
> Out[4]=  {0.44 Second,100000.}
> 
> In[5]:=  Timing[Inner[Divide,y,y]]
> 
> Out[5]=  {0.321 Second,100000.}

• Follow-Ups:
  • Re: Re: Curious Timing Results
    • From: Daniel Lichtblau <danl@wolfram.com>