Re: Timing of looping operators
- To: mathgroup at smc.vnet.net
- Subject: [mg62449] Re: Timing of looping operators
- From: carlos at colorado.edu
- Date: Thu, 24 Nov 2005 06:33:49 -0500 (EST)
- References: <200511230931.EAA20248@smc.vnet.net><dm1jrq$n55$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
The difference can be striking for built-in functions,
e.g. the dot product:
n=1000000; a=b=Table[N[i],{i,n}];
Print[Timing[a.b]];
Print[Timing[Sum[a[[i]]*b[[i]],{i,n}]]];
Print[Timing[s=0; For[i=1,i<=n,i++,s+=a[[i]]*b[[i]]] ]];
Print[Timing[s=0; Do[s+=a[[i]]*b[[i]],{i,n}] ]];
Times: 0.03, 13.2, 28.4, 19.9 sec
- References:
- Timing of looping operators
- From: dh <dh@metrohm.ch>
- Timing of looping operators