Plot f(x,y) = (x+y+xy+1) / xy = 0

 f(x,y) = (x+y+xy+1) / xy = 0

Hi, How can I plot 2D of the function above on MUPAD or Note ? It is simple 2D x, y space but I couldn't figure it out.

Thank you.

Answer 1

[Star Strider]

You can do that with the Symbolic Math Toolbox and the fcontour function, setting ‘LevelList’ to a vector of zeros:

syms x y
f(x,y) = (x+y+x*y+1) / (x*y);

figure(1)
fc = fcontour(f);
fc.LevelList = [0 0];

See the documentation on fcontour for details.

[gunmo gu]

Thank you for your help. I have another Question

1. How can I show X Y axis,....... 2. How can I add another function on Same figure ?

[Star Strider]

Use the hold function.

See the documentation on hold for details.

[Matthew]

Maybe also use fimplicit()?

f = @(x,y)(x+y+x*y+1) / (x*y)
fimplicit(f)

[Star Strider]

@Matthew — Now, yes. The fimplicit function was introduced in R2016b, so it likely wasn’t available when I posted that answer.

[Torsten]

@Matthew

But use

f = @(x,y)(x+y+x*y+1)

to avoid division by 0.

And the zero sets of both functions are equal.

Answer 2

[Ahmed]

https://www.mathworks.com/matlabcentral/answers/103972-how-to-plot-f-x-y-x-2-y-function-in-matlab