Subject: Re: [xsl] Is this the best way to compute a sigmoid function? From: "Michael Kay mike@xxxxxxxxxxxx" <xsllistservice@xxxxxxxxxxxxxxxxxxxxxx> Date: Sat, 2 May 2020 18:09:19 0000 
> On 2 May 2020, at 18:55, Costello, Roger L. costello@xxxxxxxxx <xsllistservice@xxxxxxxxxxxxxxxxxxxxxx> wrote: > > > I want to compute the result of evaluating this sigmoid function: > > 1 >  > (1 + e**x) > > That is, compute 1 divided by (1 + e raised to the x power) In recent versions of XPath, you can simply do (1 div (1 + math:exp($x))) > (However, it already appears to be mighty accurate  look at all those digits to the right of the decimal point) I hope you don't seriously believe that precision implies accuracy  that someone who claims the population of the world is 7,345,651,523 is more likely to be right than someone who says it is 7 billion. > Notice that for the variable $etotheminusxpower I specified it this way: as="xs:decimal". Should I have specified it this way: as="xs:float" instead? For calculations like this it's best to use xs:double. You don't need any more precision than this, and exponential/trigonometric functions are likely to be implemented as doubleprecision floating point by whatever underlying library is used. Michael Kay Saxonica
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Re: [xsl] Is this the best way to c, Martin Honnen martin  Date  Re: [xsl] Is this the best way to c, Dimitre Novatchev dn 
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