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From: Ethan Merritt <eamerritt@gmail.com>
Newsgroups: comp.graphics.apps.gnuplot
Subject: Re: Intermediate variables in user functions
Date: Sun, 25 Aug 2019 17:46:21 -0000 (UTC)
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On Sun, 25 Aug 2019 06:33:35 -0700, layzarc wrote:

> I have a script that works beautifully that has the following function definitions:
> 
> phi(x,y) = (1+x)/(1+sqrt(1+(x*x-1)*y))
> astig(n,x,y) = phi(x,y)*(1-phi(x,y)*y)*(n-1)**2-(phi(x,y)-n*n)*(n-1+y*(phi(x,y)-n))**2
> 
> It would be a lot cleaner if the following was possible:
> 
> phi(x,y) = (1+x)/(1+sqrt(1+(x*x-1)*y))
> astig(n,x,y) = f=phi(x,y) f*(1-f*y)*(n-1)**2-(f-n*n)*(n-1+y*(f-n))**2
> 
> Al

Use the serial evaluation operator (a,b):

    astig(n,x,y) = (f=phi(x,y) , f*(1-f*y)*(n-1)**2-(f-n*n)*(n-1+y*(f-n))**2)