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Re: Machine-precision Expfunction

• To: mathgroup at smc.vnet.net
• Subject: [mg93645] Re: Machine-precision Expfunction
• From: Bill Rowe <readnews at sbcglobal.net>
• Date: Thu, 20 Nov 2008 04:55:50 -0500 (EST)

On 11/18/08 at 7:22 AM, rschmied at gmail.com (Roman) wrote:

>Bill, I don't agree with your statement:
>In[1] := Precision[-1`*^6] Out[1] = MachinePrecision
>So there is no such conversion involved. In any case, my question
>was not about such conversions, but about avoiding arbitrary-math
>routines. Roman.

With respect to actually checking the precision in your original
example, obviously I didn't do that when i should have. But with
respect to avoiding "arbitrary-math routines" which I interpret
as meaning avoiding the overhead of Mathematica's arbitrary
precision arithmetic, the answer is simple. Just enter all
numerical parameters with a decimal point. Then by default,
Mathematica uses machine precision arithmetic through-out the
computation which will yield the fastest execution time for a
given implementation of a given algorithm. And since it takes
fewer characters to enter numerical data with a decimal point
than it does to specify a specific precision, I really don't
understand why anyone would do any thing else to invoke machine
precision computations.

• Follow-Ups:
  • RE: Re: Machine-precision Expfunction
    • From: "Ingolf Dahl" <f9aid@chalmers.se>