Hello,
Please I have difficulty to figure out way to show the steps for derivative Ur, and Uy. There are many ways I tried WolframAlpha but it doesn't work.
Clear[r, R, y, Y, k, A, B, U, Ur, Uy]
k = (4*R*r)/((y + Y)^2 + (r + R)^2);
k1 = Sqrt[(4*R*r)/((y + Y)^2 + (r + R)^2)];
A[k_] := EllipticK[k];
B[k_] := EllipticE[k];
U = -((Sqrt[R*r]/(2*Pi*k1)) *(((2 - k1^2)*A[k]) - 2*B[k]));
Ur = (1/r) D[U, y] // FullSimplify;
Uy = (-1/r) D[U, r] // FullSimplify;
Thanks