How to plot a semi-circle on the horizontal axis in MATLABs & How to shade half the cirlce?

Hello I recetly got into plotting on MATLABs and I was wondering how I could create a semi-circle on the x-axis, and shade half of the semi-cicle afterwards.

Answer 1

[Image Analyst]

See the FAQ:

https://matlab.fandom.com/wiki/FAQ#How_do_I_create_an_arc?

Answer 2

[Voss]

Npts = 101;
r = 2;
c = [0 0];
theta = linspace(0,pi,Npts);

x = c(1) + r.*cos(theta);
y = c(2) + r.*sin(theta);

fill([x(1:(Npts+1)/2) c(1) x(1)], ...
     [y(1:(Npts+1)/2) c(2) y(1)], ...
     'y', ...
     'EdgeColor','none')
hold on
plot([x x(1)],[y y(1)],'k','LineWidth',2)

axis equal