Plotting graph of an implicit function in MATLAB

Question

I am unsure about how to do a plot (graph) of an implicit function in MATLAB. Let us say a have a two-variable polynomial P and an implicit function (not solvable explicitly) P(x,y)=0. How do I plot the latter graph in the x-y coordinate system (with a grid)?

I tried to use the contour on z=P(x,y), but it gives me level curves at several levels that MATLAB chooses. I wont just the one level at z=0.

Answer 1

The entire suit of f___ where ____ is a plotting function is what you want.

For example.

syms x
syms y
fsurf(x^3*y+3*y^2*x^2-5*y^3+x*y+1)