NDSolve

*To*: mathgroup at smc.vnet.net*Subject*: [mg125236] NDSolve*From*: rf248 <rf248 at st-andrews.ac.uk>*Date*: Thu, 1 Mar 2012 05:34:47 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

Hello, I am trying to solve an initial value problem with NDSolve. However, the initial values are set on a regular singular point. When solving Bessel's differential equation, one can avoid this problem with the option SolveDelayed ->True. This however does not help with the following problem (hydrogen atom) to which the analytic solution is a Laguerre polynomial. l = 0; n = 1; a = 1; eps = -1/(2 n^2); func = r D[r R[r], {r, 2}] + (2 (a r + eps r^2) - l (l + 1)) R[r] == 0; nrad = NDSolve[{func, R[0] == 2, R'[0] == -2}, R[r], {r, 0, 100}, SolveDelayed -> True] Above, the initial values chosen correspond to an exact solution for constants l, n, a and eps. Mathematica must therefor be able to find a solution. Thanks!