如何在Matlab中绘制圆? [英] How to plot a circle in Matlab?
问题描述
我想知道如何在Matlab中绘制圆,知道中心和半径吗?我尝试了circles()
,它似乎不起作用,因为我的Matlab版本没有它.我知道我可以使用Rectangle函数来执行此操作,但这是一种相当复杂的方法,因为每次都需要找出最左边的点.
I would like to know how can I graph circles in Matlab knowing the center and radius? I have tried circles()
which does not seem to work because my Matlab version does not have it. I know I can use the Rectangle function to do so but it is a rather complex way of doing it as I would need to work out the leftmost point everytime.
难道我不知道中心和半径就画圆了吗?
Isn't there a more simple way for me to draw a circle JUST knowing center and radius?
推荐答案
Don't laugh, but the easiest would be to use the rectangle
function, indeed ;)
%// radius
r = 2;
%// center
c = [3 3];
pos = [c-r 2*r 2*r];
rectangle('Position',pos,'Curvature',[1 1])
axis equal
但将矩形的曲率设置为 1 !
but set the curvature of the rectangle to 1!
position
向量定义矩形,前两个值x
和y
是矩形的左下角.最后两个值定义矩形的宽度和高度.
The position
vector defines the rectangle, the first two values x
and y
are the lower left corner of the rectangle. The last two values define width and height of the rectangle.
pos = [ [x y] width height ]
圆的左下角角-是的,该圆具有拐角,尽管是假想的-是中心 c = [3 3]
减去半径 r = 2
,即[x y] = [1 1]
. 宽度和高度等于圆的直径,因此width = 2*r; height = width;
The lower left corner of your circle - yes, this circle has corners, imaginary ones though - is the center c = [3 3]
minus the radius r = 2
which is [x y] = [1 1]
. Width and height are equal to the diameter of the circle, so width = 2*r; height = width;
如果您不喜欢上述解决方案的平滑性,则无法通过三角函数使用明显的方法绘制实际圆.
In case you don't like the smoothness of the above solution, there is no way around using the obvious way of drawing an actual circle by use of trigonometric functions.
%// number of points
n = 1000;
%// running variable
t = linspace(0,2*pi,n);
x = c(1) + r*sin(t);
y = c(2) + r*cos(t);
%// draw line
line(x,y)
%// or draw polygon if you want to fill it with color
%// fill(x,y,[1,1,1])
axis equal
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