RE: speed
- To: mathgroup at smc.vnet.net
- Subject: [mg15625] RE: [mg15593] speed
- From: "Jean-Marie THOMAS" <jmthomas at agat.net>
- Date: Sat, 30 Jan 1999 04:28:27 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Note first that programming with Nest is faster than a do loop and
second I doubt working in machine precision gives you the same results!
Timing[x=0.3;Print[x]; Do[x=x*1.003456,{i,1,1000000}];Print[x]] 0.3`
6.47467770894613173679`10.1231*^1497 {179.94799999999989` Second,Null}
Timing[x=0.3;Print[x];Nest[# 1.003456&,x,1000000]] 0.3`
{160.210999999999792` Second,6.47467770894613173679`10.1231*^1497}
Hope this helps,
**************************************** Jean-Marie THOMAS
mailto:jmthomas at agat.net
Conseil et Audit en Ingenierie de Calcul Strasbourg, France
http://www.agat.net
****************************************
-----Original Message-----
From: Margit [mailto:mgfoehle at mch1srv.tuwien.ac.at] To:
mathgroup at smc.vnet.net
Subject: [mg15625] [mg15593] speed
Hi!
I have a question concerning the numerical speed of Mathematica:
I performed the following calculation
x=0.3;Print[x]; Do[x=x*1.003456,{i,1,1000000}];Print[x]
with Mathematica, it took about 150 seconds.
The same calculation is performed by TurboPascal in 0.4 seconds.
I guess that the difference is caused by the working precision. Does
anyone know what is the reason for this long duration and how it can be
changed?
Thanks!
Margit