How do I get Matlab to draw a graph with solutions to an equation? I tried making matlab draw a graph for a multivariable equation, but I can't figure out how to. Tried to make an array of solution then plot it, but it didn't work.

vars = [x y]
eqn = z == x^2 + 4*y^2 - 2*x + 8*y +1;
Z = solve(eqn, vars); %I don't understand the output
[X Y] = meshgrid(-4, 0.1 ,4);
surf(X, Y, Z)
%probaly not the most efficent way, but it made sense to me

[madhan ravi]

See if this does what you want :

fimplicit3(eqn)

[comment moved to answer section]

[Kjartan Thomas Madsen]

Worked like a charm, thanks!

Answer 1

[Walter Roberson]

fsurf(rhs(eqn), [-4 4 -4 4])

Answer 2

[madhan ravi]

https://in.mathworks.com/matlabcentral/answers/451955-how-do-i-get-matlab-to-draw-a-graph-with-solutions-to-an-equation-i-tried-making-matlab-draw-a-grap#comment_684885