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Recalculating values in tables?

• To: mathgroup at smc.vnet.net
• Subject: [mg63881] Recalculating values in tables?
• From: AES <siegman at stanford.edu>
• Date: Fri, 20 Jan 2006 04:32:36 -0500 (EST)
• Organization: Stanford University
• Sender: owner-wri-mathgroup at wolfram.com

If I'm evaluating a table with something like

 Table[ {initialExpressions; f1, f2, Sqrt[(f1-f2)/(f1*f2)}, {iterator} ]

where  f1, f2, f3  are slow-to-evaluate functions (possibly with 
explicit variables, which will be the same for all three calls to the 
f's), I'm tempted to assume that Mathematica will be smart enough to 
evaluate  f1, f2 and f3 just once, not three times, for each line in the 
Table.  Is this low risk?

Or should I always take the messier of route of coding these functions 
explicitly in my initialExpressions using something like

 Table[ { initialExpressions;
            g1=f1;
            g2=f2;
            g3=f3;
            g1, g2, Sqrt[(g1-g2)/(g1*g2)}, {iterator} ]

Just wondering how far to trust Mathematica in situations like this?

• Follow-Ups:
  • Re: Recalculating values in tables?
    • From: Daniel Lichtblau <danl@wolfram.com>
  • Re: Recalculating values in tables?
    • From: ggroup@sarj.ca
  • Re: Recalculating values in tables?
    • From: Sseziwa Mukasa <mukasa@jeol.com>