MATLAB: How to graph a quadratic function f(x,y) – parabola

functiongraphMATLABparabolaplotquadratic

The intention is to plot the next equation: 0==-(x+y).^2+6540.*(y.*2.6284 – x.*2.187) and get the following parabola:

I've tried several options, but I'm not able to get the parabola, what could I do?

Best Answer

Starting in R2016b, https://www.mathworks.com/help/matlab/ref/fimplicit.html

f = @(x,y) (x+y).^2 + 6540 * (y * 2.6284 - x * 2.187);
fimplicit(f, [-5000, 20000, -20000, 5000])

Related Solutions

MATLAB: How can i represent 2 functions on the same graph

One option is the fimplicit (link) function:

f1 = @(x,y) 2*x.^3-5*x-2*y.^3+1;
f2 = @(x,y) x.^4+4*y.^4.*y-6;
figure(1)
fimplicit(f1, [-10 10 -10 10])
hold on
fimplicit(f2, [-10 10 -10 10])
hold off
legend('f_1(x,y)', 'f_2(x,y)', 'Location','NW')

MATLAB: Plotting a surface in MATLAB

You need to use the meshgrid (or equivalently, ndgrid) function:

x = linspace(-1, 1);
y = linspace(-2, 2);
[X,Y] = meshgrid(x,y);
f = @(x,y) x.^2.*y./(x.^2 + y.^2);
figure(1)
surf(X,Y,f(X,Y))
grid on

I created a function for ‘f’ here, but you could as easily use it simply as:

f = X.^2.*Y./(X.^2 + Y.^2);

and then plot as:

plot(X,Y,f)

I ‘vectorised’ your code to do element-wise operations. See the documentation on Array vs. Matrix Operations for a full discussion.

Best Answer

Related Solutions

MATLAB: How can i represent 2 functions on the same graph

MATLAB: Plotting a surface in MATLAB

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