Re: Difference /recurrence equations

*To*: mathgroup at smc.vnet.net*Subject*: [mg35133] Re: [mg35127] Difference /recurrence equations*From*: Hugh Walker <hwalker at gvtc.com>*Date*: Tue, 25 Jun 2002 19:55:09 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On Tuesday, June 25, 2002, at 02:42 AM, Andrew Biggs wrote: > I'm new to Mathematica and am having trouble with inputting the > equations I'm looking to solve. I know the basic input of RSolve, but > can't quite get it. Here's a sample problem, if anyone could show me > how to input into RSolve I can probably run with the ball after that. > > y(t+2) - 2Y(t+1) + 3Y(1) = 4 > > With the part in brackets being a subscript denoting time. I know it > sounds dumb, but I just don't know the input notatin well enough to > get a problem typed in correctly, and the Mathematica book is a little > overwhelming. > > Any help greatly appreciated! > > Andrew First, load the AddOn RSolve package: <<DiscreteMath`RSolve Then apply to your problem. For example, for the given difference equation and initial conditions {y[0]==0, y[1]==1}, sol=RSolve[ {y[k+2] - 2*y[k+1] + 3*y[k] == 4, y[0]==0, y[1]==1}, y[k], k] ============ Hugh Walker Gnarly Oaks