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Re: ANN: Port of Airy Function Code to Forth

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On Monday, April 15, 2013 2:46:35 PM UTC-5, Marcel Hendrix wrote:
> krishna.myneni@ccreweb.org writes RE: ANN: Port of Airy Function Code to Forth
> 
> 
> 
> > A first version of my port of the Fortran routine, JAIRY, for computing the
> 
> > Airy function, and its derivative, for a real argument, is available at
> 
> 
> 
> > ftp://ccreweb.org/software/fsl/extras/jairy.fs
> 
> [..]
> 
> > TESTING JAIRY
> 
> > ok
> 
> 
> 
> I get one error, for -10.0e jairy .
> 
> According to Wolfram Alpha, the result should be:
> 
> 
> 
>   t{ -10.0e jairy -> 4.0241238486443190689430e-2  9.962650441327900e-1   ?}t
> 
> \                                  ^^^^^^^^^^
> 
> However, the current file says
> 
>   t{ -10.0e jairy -> 4.024123848644296e-2         9.962650441327906e-1  ?}t
> 
> \                                  ^^^
> 
> 
> 
> iForth computes:
> 
> FORTH> -10e jairy cr fswap +e. space +e.
> 
>  4.0241238486443971872e-0002  9.9626504413279069178e-0001 ok
> 
> 
> 
> This tests OK with the Alpha values, but not with the original test result.
> 
> 
> 
> -marcel

Hmmm.... Maxima says differently:

(%i66) fpprec: 40;
(%o66)                                40
(%i67) bfloat(airy_ai(-10.0b0)), numer;
(%o67)           4.024123848644296091991989783309691119939b-2
(%i68) bfloat(airy_dai(-10.0b0)), numer;
(%o68)           9.962650441327906003508019239234272390604b-1


That doesn't mean Maxima is right, though. Have to check the MPFR library -- does it have a built in Airy function?

Krishna

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ANN: Port of Airy Function Code to Forth krishna.myneni@ccreweb.org - 2013-04-14 19:36 -0700
  RE: ANN: Port of Airy Function Code to Forth mhx@iae.nl (Marcel Hendrix) - 2013-04-15 21:46 +0200
    Re: ANN: Port of Airy Function Code to Forth krishna.myneni@ccreweb.org - 2013-04-15 16:32 -0700
      Re: ANN: Port of Airy Function Code to Forth krishna.myneni@ccreweb.org - 2013-04-15 17:54 -0700

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