# Shapes in MATLAB®

How to plot bais Shapes in MATLAB® with Plotly.

## Circle

r = 10;
fig = figure;
hold on

th = 0:pi/100:2*pi;
xunit = r * cos(th);
yunit = r * sin(th);
plot(xunit, yunit);

hold off
axis square;

fig2plotly(gcf);


Plot A Unit Circle in Complex Plane

theta = 0:pi/100:2*pi;
r = 1;
z = r*cos(theta) + i*r*sin(theta);

fig = figure;
plot(z);

fig2plotly(gcf);


## Ellipse

t=0:0.1:2*pi;
x=2*cos(t);
y=3*sin(t);
plot(x,y);
grid on;

fig2plotly(gcf);


## Covariance Ellipse

num = 50;
X = [ mvnrnd([0.5 1.5], [0.025 0.03 ; 0.03 0.16], num) ; ...
mvnrnd([1 1], [0.09 -0.01 ; -0.01 0.08], num)   ];
G = [1*ones(num,1) ; 2*ones(num,1)];
fig = figure;

gscatter(X(:,1), X(:,2), G)
axis equal, hold on

for k=1:2
idx = ( G == k );

Mu = mean( X(idx,:) );
X0 = bsxfun(@minus, X(idx,:), Mu);

[V D] = eig( X0'*X0 ./ (sum(idx)-1) );
[D order] = sort(diag(D), 'descend');
D = diag(D);
V = V(:, order);

t = linspace(0,2*pi,100);
e = [cos(t) ; sin(t)];
VV = V*sqrt(D);
e = bsxfun(@plus, VV*e, Mu');

plot(e(1,:), e(2,:), 'Color','k');

end

fig2plotly(gcf);