How to draw a rotated ellipse without any toolbox?

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ManKit Tse
ManKit Tse 2012-8-28
评论： Vivek Bhartiya 2020-3-30
I need to draw rotated ellipse on a Gaussian distribution plot by surf. I am using a student version MATLAB. Can i still draw a ellipse center at estimated value without any toolbox that required money to buy. I search on internet somebody write ellipse function and allow to download. Are they work well on surf plot.

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采纳的回答

Babak
Babak 2012-8-28
编辑：Babak 2012-8-28
t = linspace(0,2*pi,1000);
theta0 = pi/6;
a=2;
b=1;
x = a*sin(t+theta0);
y = b*cos(t);
plot(x,y)
axis equal
  3 个评论
显示 1更早的评论
Image Analyst
Image Analyst 2012-9-2
Well yeah, because if a or b is really close to zero, the width is really close to zero and the ellipse is essentially almost a line. And a line has to lie along the raster lines on your monitor. The line can be on line 1 or on line 2. You can't have pixels going across the screen at line 1, line 1.01, line 1.02, etc. up to line 1.88 or whatever. It's got to be just on line 1 or on line 2, not on fractional lines. For further reading: http://en.wikipedia.org/wiki/Jaggies
Gabriel Hernandez
Gabriel Hernandez 2019-12-9
编辑：Gabriel Hernandez 2019-12-9
This code did not work for me. The answer posted below is much more accurate.

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更多回答（1 个）

Oleksii Sidorov
Oleksii Sidorov 2018-2-26
My version with general parametric equation of rotated ellipse, where 'theta' is angle of CCW rotation from X axis (center at (x0, y0))
t = linspace(0,2*pi,100);
theta = deg2rad(105);
a=2;
b=1;
x0 = 0.15;
y0 = 0.30;
x = x0 + a*cos(t)*cos(theta) - b*sin(t)*sin(theta);
y = y0 + b*sin(t)*cos(theta) + a*cos(t)*sin(theta);
figure;
plot(x,y);
axis equal;
  2 个评论
Gabriel Hernandez
Gabriel Hernandez 2019-12-9
Your code worked perfectly for me, much better than the one from the accepted answer. Thank you!
Vivek Bhartiya
Vivek Bhartiya 2020-3-30
Fantastic work. It was quite hard to find a functional code.

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