Re: 4th order DE, NDSolve no solution, why?

*To*: mathgroup at smc.vnet.net*Subject*: [mg15813] Re: 4th order DE, NDSolve no solution, why?*From*: Paul Abbott <paul at physics.uwa.edu.au>*Date*: Fri, 12 Feb 1999 18:39:36 -0500 (EST)*Organization*: University of Western Australia*References*: <79jcmg$r4a@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Kevin J. McCann wrote: > That is the first I have seen. Wonder where I got the idea? I guess I > was thinking about eigenvalue problems like > > y''[x] + y[x] == 0, y[0]==0,y[1]==0 > > Which NDSolve will do, but it gives y=0 only, not all of the other > possibilities. Actually, NDSolve is correct to return y=0 for this problem. However, I think you are thinking of DSolve[{y''[x]+y[x]==0, y[0]==0, y[Pi]==0}, y[x], x] which NDSolve can solve. However, it does not return the general solution to DSolve[{y''[x]+ n^2 y[x]==0, y[0]==0, y[Pi]==0}, y[x], x] Cheers, Paul ____________________________________________________________________ Paul Abbott Phone: +61-8-9380-2734 Department of Physics Fax: +61-8-9380-1014 The University of Western Australia Nedlands WA 6907 mailto:paul at physics.uwa.edu.au AUSTRALIA http://www.physics.uwa.edu.au/~paul God IS a weakly left-handed dice player ____________________________________________________________________