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Mar 03, 2017
02:18 PM

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Mar 03, 2017
02:18 PM

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:

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

Solved! Go to Solution.

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Mar 03, 2017
04:32 PM

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13 REPLIES 13

Mar 03, 2017
03:57 PM

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Mar 03, 2017
03:57 PM

Hi Shawn Fan,

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

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

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

Best Regards

FM

Mar 03, 2017
04:32 PM

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Mar 03, 2017
05:00 PM

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Mar 03, 2017
05:00 PM

Lace

Mar 03, 2017
05:05 PM

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Mar 03, 2017
05:05 PM

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

Mar 07, 2017
01:26 AM

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Mar 03, 2017
05:08 PM

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Mar 03, 2017
05:08 PM

Like this, there is a "." sign automatically inserted when I type Beta

Mar 03, 2017
05:25 PM

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Mar 03, 2017
05:25 PM

And than use infix operator!

Mar 03, 2017
10:16 PM

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Mar 03, 2017
10:16 PM

Thank you!

Unfortunately I am using Mathcad Prime now and it appears that Prime cancels the infix operator (so sad)

I would use the convergence of say f(x,y) <= 0 to generate a solid(with many points) circle then.

So sad Prime cancels this useful function that looks like a devolve.

Considering Matlab recommends fplot over the old ezplot, while fplot does not come with the same function as ezplot, I feel a little bit better, LOL...

Still, thank you Valery, thank you FM!

Mar 04, 2017
03:18 AM

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Mar 05, 2017
03:36 AM

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Mar 05, 2017
03:36 AM

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

Mar 05, 2017
08:06 PM

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Mar 05, 2017
08:06 PM

Thank you so much Werner!

This function is very quick!

I will refer to Mezentsev in my homework.

Thank you!

Mar 06, 2017
05:04 AM

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Mar 06, 2017
05:04 AM

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

Viktor

Viktor

Mar 07, 2017
12:30 PM

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Mar 07, 2017
12:30 PM

Here is a way to simulate it in Prime

Its a pity its not possible to do it the way it works in real Mathcad

Alas - its Prime - what did we expect?