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Re: Folium of Descartes
From: |
Muthiah Annamalai |
Subject: |
Re: Folium of Descartes |
Date: |
Fri, 16 Nov 2007 18:25:31 -0600 |
On Nov 16, 2007 1:45 PM, Giovanni Lovato <address@hidden> wrote:
> Muthiah Annamalai wrote:
> > Giovanni Lovato wrote:
> >> How can I draw the Folium of Descartes in Octave?
> >> In Matlab I did:
> >>
> >>
> >>>> f = sym('x^3-x^2+y^2');
> >>>> ezplot(f)
> >>>>
> >>
> >> Various Octave tutorials explain how to draw simple functions in one
> >> variable, but I can't find a way to draw functions in two (or more)
> >> variables.
> >> I'm a very newbie of Octave (and Matlab too), maybe it's silly
> >> questions - in this case, sorry :)
> >>
> >> Thanks in advance,
> >> G.L.
> >>
> > Apparently the right (I dont have Matlab, so I assume here) way, to do
> > this is
> >
> > func = inline ( vectorize ( 'x^3-x^2+y^2' ) );
> > y = linspace(-2*pi, + 2*pi, 100);
> > x = y;
> >
> > z = func(x,y);
> > plot3 (x,y,z)
>
> Thank you for the interest!
> BTW the plot won't display a folium-like curve, but a totally different
> (I think!) curve.
>
> E.g., in Matlab I get:
>
> f = sym('x^3-x^2+y^2');
> ezplot(f)
>
> \ |
> \ |
> \ | __
> \ | / \
> _____\|/____\______
> /|\ /
> / | \__/
> / |
> / |
> / |
>
> Which is the correct folium.
>
> In Octave:
>
> f = inline(vectorize(x^3-x^2+y^2);
> x = linspace(-2*pi, +2*pi, 100);
> y = x;
> plot(f(x,y))
>
> | /
> | _/
> | /
> | _/
> | /
> ______ ___|___/ _________
> _/ |
> / |
> _/ |
> / |
> / |
>
> Okay, the ASCII-drawings are not so beautiful but I hope they'll render
> the idea :)
>
>
> G.L.
> --
> mail: address@hidden
> web: http://heruan.my.aldu.net
>
Im sorry for flooding the list. I am using a new mail client, but
thats no excuse.
I think you want to plot the 'implicit' functions here in the ezlpot().
I think I missed that point earlier.
-Muthu