Re: newbie: diff equation

*To*: mathgroup at smc.vnet.net*Subject*: [mg96986] Re: newbie: diff equation*From*: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>*Date*: Sun, 1 Mar 2009 04:55:26 -0500 (EST)*References*: <200902261301.IAA26650@smc.vnet.net> <go8hpb$ks4$1@smc.vnet.net>

Not only for differential equations, but for all equations. == is the equals Function, = is the Set function. Cheers -- Sjoerd On Feb 27, 1:11 pm, "Ned Lieb" <okty.gy.... at gmail.com> wrote: > You have to use two equals signs instead of one when inputting a > differential equation. > > -----Original Message----- > From: Mike [mailto:atkins1... at yahoo.com] > Sent: Thursday, February 26, 2009 8:01 AM > Subject: newbie: diff equation > > My problem is very simple, I'm sure someone can help me out quickly. I am > trying to solve some systems of differential equations a bit like a parti= cle > in a box (QM) so I started with this basic problem which I know how to so= lve > just to make sure I am entering everything ok, but I can't even get it to > work. > > I want to solve f''[x]= - m^2 f[x] > > with f[0] = 0 and f[Pi] = 0 > > this is obviously only solvable with the condition on m being integer but= if > I do DSolve on the above with the boundary conditions I just get f=0. H= ow > can I get mathematica to solve this and give me the conditions on m? I ne= ed > to solve much more general problems of this type. I hope someone can help=