How to plot an Ellipse?

Question

Artur Avazov 2016-2-25

0
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https://ww2.mathworks.cn/matlabcentral/answers/270028-how-to-plot-an-ellipse

回答： Muhammad Usman Saleem 2016-2-25

在 MATLAB Online 中打开

Good day, dear users,

I started to study MATLAB language and now I would like to plot an ellipse from the data array.

I have this data for plotting several ellipses:

Here will be [c1 c2 a1 a2] correspondingly. Every line is for one ellipse.

    EllipsesData =
 300    82    70
  65    12    12
 150    12    12
  38    12    12
 127    12    12
 251    20    16
 180    47    37
 169    75    50
 257    41    32
 353    25    30
 280    14    22
 355    24    17
 355    24    17

I have created an array and saved it in EllipsesData.dat. Further, I will call the values from this file. The equation defining an ellipse is following:

(x - c1).^2 ./ a1^2 + (y - c2).^2 ./ a2^2 <= 1

The main code for plotting an ellipse I did is here:

    load EllipsesData.dat;
x = input('Enter the x coordinate');
y = input('Enter the y coordinate');
c1 = EllipsesData(1,1);
c2 = EllipsesData(1,2);
a1 = EllipsesData(1,3);
a2 = EllipsesData(1,4);
ellipse1 = (x - c1).^2 ./ a1^2 + (y - c2).^2 ./ a2^2 <= 1;
plot(ellipse1)
axis([x-10 x+10 y-10 y+10]);
grid on;
xlabel('x');
ylabel('y');
title('Ellipse');

After I launch it I get the empty figure

Could you please help me with this thing? Thank you in advance for your clarifying!

Moreover, I would like to plot all the ellipses in one figure, so for this it seems to me that I will need to use switch-case(number), input('number for plotting 'number' ellipse), hold on function.