Timing of Table
- To: mathgroup at smc.vnet.net
- Subject: [mg43227] Timing of Table
- From: "Mariusz Jankowski" <mjkcc at usm.maine.edu>
- Date: Wed, 20 Aug 2003 22:25:28 -0400 (EDT)
- Organization: University of Maine System/MSLN
- Sender: owner-wri-mathgroup at wolfram.com
Dear Mathematica Users,
Can someone explain the timing difference between the following two code
samples. I am guessing it has to do with the auto-compiler, but even if I am
correct, I would like to know more.
Slow version:
n=m=100;
Timing[Do[Table[1,{i,1,n},{j,1,m}],{1000}];]
Fast version:
n=m=100;
Timing[Do[Table[1,{i,1,n},Evaluate[{j,1,m}]],{1000}];]
which is as fast as
Timing[Do[Table[1,{i,1,100},{j,1,100}]],{1000}];]
I also noticed that only the outermost iterator needs to be wrapped in
Evaluate. Why(?)
Thanks, Mariusz