Defining a variable from an error message (NDSolve::ndsz)

*To*: mathgroup at smc.vnet.net*Subject*: [mg122265] Defining a variable from an error message (NDSolve::ndsz)*From*: Jonathan Frazer <J.Frazer at sussex.ac.uk>*Date*: Sat, 22 Oct 2011 06:10:31 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

Hi Everyone, Using the example from the NDSolve::ndsz section in the documentation centre, evaluating NDSolve[{(2 - f[x]) f'[x] == f[x], f[0] == 1}, f, {x, 0, 5}] gives the error message "NDSolve:ndsz : At x == 0.38629402687577696`, step size is effectively zero; singularity or stiff system suspected". What I would like to do is be able to automatically define a variable xdanger = 0.38629402687577696 so that I can use it in a subsequent part of the code. Does anyone have a suggestion for how I might do this? Many thanks, Jonny P.S. In similar problems I usually can make use of Check one way or another but in this case I want to be able to use the variable xdanger to make an inequality. For this reason, I don't think Check is applicable.

**Follow-Ups**:**Re: Defining a variable from an error message (NDSolve::ndsz)***From:*Oliver Ruebenkoenig <ruebenko@wolfram.com>