hwsplr.f

SUBROUTINE HWSPLR SOLVES A FINITE DIFFERENCE APPROXIMATION TO THE HELMHOLTZ EQUATION IN POLAR COORDINATES: (1/R)(D/DR)(R(DU/DR)) + (1/R**2)(D/DTHETA)(DU/DTHETA) + LAMBDA*U = F(R,THETA). REFERENCE: SWARZTRAUBER,P. AND R. SWEET, ’EFFICIENT FORTRAN SUBPROGRAMS FOR THE SOLUTION OF ELLIPTIC EQUATIONS’.