[Date Index] [Thread Index] [Author Index]
RE: Re: Machine-precision Expfunction
An answer in the style of Jens: In:= Precision[Exp[-1000.]] Out= 12.9546 ????? Regards Ingolf -----Original Message----- From: Bill Rowe [mailto:readnews at sbcglobal.net] Sent: den 20 november 2008 10:56 To: mathgroup at smc.vnet.net Subject: [mg93674] [mg93645] Re: Machine-precision Expfunction On 11/18/08 at 7:22 AM, rschmied at gmail.com (Roman) wrote: >Bill, I don't agree with your statement: >In := Precision[-1`*^6] Out = 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.