# Math Help - MATLAB - plotting a quadratic

1. ## MATLAB - plotting a quadratic

Quick question:
How do I plot the following in MATLAB:
$3x^2 - 4xy + 3y^2 = 20$
cheers

edit:
nevermind, think I've go it now:
>> syms x y; quad = '3*x^2-4*x*y+3*y^2-20'; ezplot(quad,[-4,4,-4,4])
appears to work.

2. Originally Posted by Dr Zoidburg
Quick question:
How do I plot the following in MATLAB:
$3x^2 - 4xy + 3y^2 = 20$
cheers

edit:
nevermind, think I've go it now:
>> syms x y; quad = '3*x^2-4*x*y+3*y^2-20'; ezplot(quad,[-4,4,-4,4])
appears to work.
When asking questions about Matlab please make it clear if you want to use the symbolic processor (some of us think of this as an extra - since we don't get it unless we pay many £100's extra).

(The symbolics are done by Maple not by Matlab so its always odd to see such questions presented as Matlab questions)

RonL

3. sorry, I didn't know that symbolics wasn't a standard part of MATLAB. I know eff-all about using MATLAB (this year is my first time ever). I found the above solution on-line and tried it out. It worked, which I guess means the MATLAB I'm using has MAPLE installed.

Out of interest, how would I plot the above equation without using sym?