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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