Re: Re: RE: Comparison between Mathematica and other

• To: mathgroup at smc.vnet.net
• Subject: [mg92547] Re: [mg92537] Re: [mg92527] RE: [mg92378] Comparison between Mathematica and other
• From: "peter lindsay" <pl.0 at me.com>
• Date: Sat, 4 Oct 2008 06:17:14 -0400 (EDT)
• References: <200809301133.HAA21932@smc.vnet.net>

```I agree. The object is to persuade people how accessible Mathematica is, not
how incredibly learned and expert the users need to be.
Peter

2008/10/3 Murray Eisenberg <murray at math.umass.edu>

> I'd exercise caution before presenting such an example to people whom
> you're trying to convince to turn to Mathematica.  all the vertical
> strokes, including those in the brackets, make this look like a jumble
> of incomprehensible symbols.  The effect could be precisely the opposite
> of what you intend.
>
> Ingolf Dahl wrote:
>
> > I do not know how this is example is interesting or how it is done in
> other
> > systems, but once, 14 years back, it convinced me that I should use
> > Mathematica for a specific problem. I wanted to sort the eigenvectors of
> a
> > real matrix according to decreasing size of the real part of the
> > eigenvalues. For complex eigenvalue pairs I wanted the eigenvalue with
> > positive imaginary part sorted first. I just wanted to specify the
> sorting
> > rule, and did not feel for writing the sorting algorithm from scratch.
> This
> > is how I solved it in Mathematica
> >
> > Transpose[
> >  Sort[Transpose[Eigensystem[RandomReal[{-1, 1}, {6, 6}]]],
> >
> >   Re[#2[[1]]] < Re[#1[[1]]] ||
> >     Re[#2[[1]]] == Re[#1[[1]]] && Im[#2[[1]]] < Im[#1[[1]]] &]]
> >
> > I think this also is a good example of the use of functional programming,
> > and it helped me to get in to it.
> > In Mathematica we are thus able to sort any kind of "objects" with any
> kind
> > of sorting criteria, thanks to the generality of the language.
>
> --
> Murray Eisenberg                     murray at math.umass.edu
> Mathematics & Statistics Dept.
> Lederle Graduate Research Tower      phone 413 549-1020 (H)
> University of Massachusetts                413 545-2859 (W)
> 710 North Pleasant Street            fax   413 545-1801
> Amherst, MA 01003-9305
>
>

```

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