Create an ellipse at 45 degree angle
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Michelle Patrick-Krueger
on 22 Nov 2022
Commented: Star Strider
on 22 Nov 2022
I am trying to create an ellipse of 1 standard deviation around the mean of a scatter plot. The scatter plot is a smear of points at a 45 degree angle.
I'm able to create an ellipse using:
rectangle('Position',cnr,'Curvature',[1,1]);
Where 'cnr' is [x y w h] of the ellpse, with the xy being the lower left corner of where the rectangle would start, but I haven't found anything on how to rotate the ellipse.
Thank you for any help you can give.
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Accepted Answer
Star Strider
on 22 Nov 2022
Try this instead —
v = linspace(0, 1);
rx = 0.5;
ry = 0.25;
x = rx*cos(2*pi*v + pi/4);
y = ry*sin(2*pi*v);
figure
plot(x, y)
grid
axis([-1 1 -1 1])
axis('equal')
Mak e appropriate changes to get the result you want.
.
3 Comments
Torsten
on 22 Nov 2022
I think a rotation by 45 degrees should be like this:
v = linspace(0, 1);
rx = 0.5;
ry = 0.25;
x = rx*cos(2*pi*v);
y = ry*sin(2*pi*v);
xx = x*cosd(45) - y*sind(45);
yy = x*sind(45) + y*cosd(45);
figure
plot(xx, yy)
grid
axis([-1 1 -1 1])
axis('equal')
Star Strider
on 22 Nov 2022
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