[英]How to plot a circle in Matlab? (least square)
I am trying to plot a circle's equation-regression on x and y, but I do not know how to proceed.我试图在 x 和 y 上绘制圆的方程回归,但我不知道如何进行。 Any suggestions?
有什么建议? (I want a circle to connect the points thru least square solution)
(我想要一个圆通过最小二乘解决方案连接点)
x = [5; 4; -1; 1];
y = [3; 5; 2; 1];
% circle's equation: x^2+y^2 = 2xc1+2yc2+c3
a = [2.*x,2.*y,ones(n,3)]
b = [x.^2 + y.^2];
c = a\b;
How do I plot the circle after this在此之后我如何绘制圆圈
There are a couple of ways how to plot a circle in matlab:在 matlab 中有两种绘制圆的方法:
'o'
marker in plot and the 'MarkerSize'
name-value pair to set the radius of the circle'o'
标记和'MarkerSize'
名称-值对来设置圆的半径vscircle
function In your case, I would go with the first option, since you maintain in control of the circle size.vscircle
函数绘制圆形图像在您的情况下,我会选择第一个选项,因为您可以控制圆形大小。rectangle(...,'Curvature',[1 1])
function [EDITED: thx to @Cris Luengo]rectangle(...,'Curvature',[1 1])
函数[编辑:感谢@Cris Luengo] So here is a plotting function所以这是一个绘图函数
function circle(x,y,r)
%x and y are the coordinates of the center of the circle
%r is the radius of the circle
%0.01 is the angle step, bigger values will draw the circle faster but
%you might notice imperfections (not very smooth)
ang=0:0.01:2*pi+.01;
xp=r*cos(ang);
yp=r*sin(ang);
plot(x+xp,y+yp);
end
So with your (corrected) code, it looks like this所以用你的(更正的)代码,它看起来像这样
x = [5; 4; -1; 1];
y = [3; 5; 2; 1];
% circle's equation: x^2+y^2 = 2xc1+2yc2+c3
a = [2.*x,2.*y,ones(length(x),1)];
b = [x.^2 + y.^2];
c = a\b;
x_m = c(1)/2;
y_m = c(2)/2;
r = sqrt(x_m^2 + y_m^2 -c(3));
% plot data points
plot(x,y,'o')
hold on
% plot center
plot(x_m,y_m,'+')
% plot circle
circle(x_m,y_m,r)
hold off
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