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From: Mauro <pippo@hotmail.com>
Newsgroups: comp.graphics.apps.gnuplot
Subject: Re: Function defined by a while loop
Date: Tue, 28 Jun 2011 11:56:13 +0200
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Il 27/06/2011 22:00, Hans-Bernhard Bröker ha scritto:
> On 27.06.2011 11:50, Antonio Lo Turco wrote:
>
>> Obviously I tried and it doesn't work!
>
> Of course it doesn't. while is a _command_, not an expression. You can't
> use it in the middle of an expression, like the one you use to define a
> function.
>
>> However I would like (and I'm not able) to implement such solution as
>> a user defined function.
>
> The only way there is recursion. But that will only work reasonably well
> for a _one_parameter_ loop. You loop over 'x' and 'i' simultaneously.
> That doesn't map cleanly to recursion over a single variable.
>
> Well, unless you make them the real and imaginary part of a complex
> number that is:
>
> iterate_f(x_i, x0, eps, maxiter) = \
> ((abs(real(x_i) - x0) < eps) || (imag(x_i) > maxiter)) \
> ? x_i \
> : iterate(f(real(x_i)) + (imag(x_i)+1)*{0,1}, x0, eps, maxiter)
>
> print iterate(x0,x0,eps,maxiter)

Thank you indeed!!!
Furthermore, it doesn't need while construct.
Nevertheless,I must congratulate all the Gnuplot development team for 
improving this unvaluable tool. The introduction of if, while and do for 
iterative constructs gives a further cut above to its practicality 
(maybe not for the functions ;-)).

Best regards

Mauro