情節矢量場與箭袋極座標表示在MATLAB

Question

我想繪製在極座標表達瞭如下的向量場：

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

現場應該看起來像figure P3.20：

Answer 1

最困難的部分是將極座標轉換爲歐幾里德座標：

[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)