Hi,

Does anyone know where to find a Ruby /inverse/ error function?^1

## Thanks,

Bil kleb

http://fun3d.larc.nasa.gov

[1] See for example http://en.wikipedia.org/wiki/Error_function

Hi,

Does anyone know where to find a Ruby /inverse/ error function?^1

Bil kleb

http://fun3d.larc.nasa.gov

[1] See for example http://en.wikipedia.org/wiki/Error_function

-------- Original-Nachricht --------

Datum: Sat, 14 Jun 2008 10:04:25 +0900

Von: Bil K. [email protected]

An: [email protected]

Betreff: Math::erfinv inverse error function

Hi,

Does anyone know where to find a Ruby /inverse/ error function?^1

## Thanks,

Bil kleb

http://fun3d.larc.nasa.gov[1] See for example http://en.wikipedia.org/wiki/Error_function

Dear Bill,

you can use Shin-ichiro Hara’s statistics2 package

http://raa.ruby-lang.org/project/statistics2/ .

It has functions for calculating the integral of the Normal Function and

its inverse, and then there

is the following relation from the Wikipedia article you cited:

The inverse of \Phi, is known as the normal quantile function, or probit function and may be >>expressed in terms of the inverse error function as

\operatorname{probit}§ = \Phi^{-1}§ = \sqrt{2},\operatorname{erf}^{-1}(2p-1) = -\sqrt{2},\operatorname{erfc}^{-1}(2p).

Another option would be to use the rsruby interface to the R statistical

language.

http://rubyforge.org/projects/rsruby/

http://www.r-project.org/

Best regards,

Axel

Axel E. wrote:

you can use Shin-ichiro Hara’s statistics2 package

Excellent; thanks.

Another option would be to use the rsruby interface to the R statistical language.

Unfortunately, I’ve never managed to get R installed on

my OS X box. I haven’t honestly tried harder than sudo

port install.

Thanks again,

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