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1-Visitor
March 3, 2017
Solved

Is there a way to plot a function of (x,y) like ezplot in Matlab?

Hi, guys

I want to plot the function:

f(x,y) = x^2 + y^2 +x*y - 3600, bounded with f(x,y) <=0;

Just like the graph shown below:

untitled.jpg

The figure is plotted with ezplot in Matlab.

function a=elp1(x,y)

     a=x.^2+y.^2-60^2-x.*y;

end

figure(1)

h1=ezplot('elp1',[-90,90,-90,90]);

So far I haven't figured out an alternative in Mathcad that can do this.

Could you help me with some ideas?

Thank you very much!

Best

Shawn

24-Ruby IV
March 3, 2017

One general method for any f(x, y)

f-x-y.png

13 replies

21-Topaz II
March 3, 2017

Hi Shawn Fan,

your function is a quadric which can be plotted as follows:

Shawn 0.jpg

the 2D plot looks like the intersection of the quadric with a plane parallel to the xy plane (z=f(x,y)=a).

Shawn 1.jpg

For me this is the most simple and basic method ...

Shawn 2.jpg

Best Regards

FM

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24-Ruby IV
March 3, 2017

One general method for any f(x, y)

f-x-y.png

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24-Ruby IV
March 3, 2017

Lace

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sfan1-VisitorAuthor
1-Visitor
March 3, 2017

Thank you Valery!

This is very helpful!

Could you give me some hint on how you apply the approximate equal?

I use a Greek beta letter to substitute your approximate equal sign since I don't know how to input it in Prime.

When I type f(x,y) and the beta sign, Mathcad will always place a "." in between the two terms, making that beta a variable rather than an operator.

Best

Shawn

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Werner_E
25-Diamond I
March 5, 2017

An ingenious method implemented by Viacheslav  N. Mezentsev to do implicit 2D and 3D plots (even for Prime) can be found here:

Re: implicitplot2d()

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sfan1-VisitorAuthor
1-Visitor
March 6, 2017

Thank you so much Werner!

This function is very quick!

I will refer to Mezentsev in my homework.

Thank you!

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1-Visitor
March 6, 2017

Another method from Viacheslav A.Tarasov. It works in MC 15 but does not work in the Prime (why?).

ellipse_VAT.png

Viktor

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