Re: Curious Timing Results
- To: mathgroup at smc.vnet.net
- Subject: [mg38668] Re: Curious Timing Results
- From: Chris Grant <grant at math.byu.edu>
- Date: Sat, 4 Jan 2003 07:25:55 -0500 (EST)
- Organization: Brigham Young University
- References: <av36rc$g08$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Thanks to those that pointed out that
x = Table[2.,{i,100000}];
creates a Packed Array but
y = Table[If[i<1000000,2.,i],{i,100000}];
doesn't. The Mathematica documentation says:
"When appropriate, large lists and nested lists of numbers are
automatically stored as packed arrays of machine-sized integers
or real numbers."
Does anyone know anymore details about what Mathematica considers
"appropriate" in this context? When fine-tuning code for
efficiency, it would be nice to be able to predict what data
structures Mathematica is creating.