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Math Help - MATLAB - plotting a quadratic

  1. #1
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    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.
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by Dr Zoidburg View Post
    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
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  3. #3
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    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?
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