# Elliptic Boundary Value Problem: Lapalce and Polar Coordinates

(lap) means the Laplacian

Vrr means the second derivative of V with respect to r

V(theta theta) means the second derivative of V with respect to theta

Solve:

(lap)V(r,theta)= Vrr+(1/r)Vr+(1/r^2)V(theta theta)=0

0 < r < 1, -(pi) < theta < pi

V(1,theta) = {1, -(pi/2) < theta < (pi/2)

{0, elsewhere

Please show all work including the derivation of any eigenvalues or eigenvectors.

Thank you

https://brainmass.com/math/numerical-analysis/elliptic-boundary-value-problem-laplace-polar-coordinates-10845

#### Solution Preview

Please see the attached doc file.

We have:

We consider:

Therefore by substitution we have:

and we can simplify as:

This must be a constant. The constant can be positive, negative or zero. In these kinds of problem, the positive choice works. We call that k^2. Then:

k must be a whole number according ...

#### Solution Summary

This shows how to solve an elliptic boundary value problem with Laplace and polar coordinates. The means for the second derivative with respect to theta are given.