Compute Induced Electric Field

Calculate the induced electric field using the integral expression.

In this paper, the integral expression for calculating the induced electric field is given by analogy to the Biot-Savart Law. The expression is proved by Helmholtz theorem and Maxwell equations. Based on the method, the paper discussed the distribution of the induced electric field generated by magnetic field in square, triangle and arbitrary polygon area.
For more details about this method, see (in Chinese):
https://phymhan.github.io/pdf/electric_field.pdf
Examples:
% define a L-shaped polygon
L_shapled_polygon = [2,2;8,2;8,5;4.9,4.9;5,8;2,8];
px = L_shapled_polygon(:,1);
py = L_shapled_polygon(:,2);
% compute the induced electric field
[x,y] = meshgrid(0:0.5:10);
[Ex,Ey] = CurlPoly([px,py],x,y);
E = sqrt(Ex.^2+Ey.^2);
figure
surfc(x,y,E)
figure
hold on
quiver(x,y,-Ex,-Ey)
contour(x,y,E,20)
plot([px;px(1)],[py;py(1)],'r')