In practical calculation, the infinite series in Equations C-16 to C-19 are truncated to only
Nterms. Together with Equations C-20 to C-23, there are a total of 4N + 4 equations to solve
for B, q', {(rn and {q}, me [-N,N]. Subsequently, {rl) and {qZ) are solved from
Equations C-12, C-14, and C-23 to C-26. Finally, {r,}, {r,}), {qZ} and {q}) are used to
construct R(,;) and Q(,;) in Equation 4-37 and Equation 4-38, and they are used to solve for
Vr(x, y) in Equation 4-29.