在MATLAB中用quiver绘制极坐标表示的矢量场

我想绘制以下以极坐标表示的向量场：

E = r * R  % (i am using big R to represent r^ hat). 

[x,y] = meshgrid(-5:1:5,-5:1:5);

r = sqrt(x.^2 + y.^2); % r in function of (x, y)
theta = atan2(y, x); % theta in function of (x, y)

u = r.*cos(theta); % x component of the vector field
v = r.*sin(theta); % y component of the vector field

quiver(x, y, u, v)

该字段应类似于：

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最困难的部分是将极坐标转换为欧几里德坐标：

E = r * R  % (i am using big R to represent r^ hat). 

[x,y] = meshgrid(-5:1:5,-5:1:5);

r = sqrt(x.^2 + y.^2); % r in function of (x, y)
theta = atan2(y, x); % theta in function of (x, y)

u = r.*cos(theta); % x component of the vector field
v = r.*sin(theta); % y component of the vector field

quiver(x, y, u, v)