Re: Difference /recurrence equations

*To*: mathgroup at smc.vnet.net*Subject*: [mg35174] Re: Difference /recurrence equations*From*: Peter Pein <petsie at arcor.de>*Date*: Fri, 28 Jun 2002 02:31:05 -0400 (EDT)*Organization*: Arcor*References*: <af990o$8u$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

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 > Hi Andrew, first load the Package: <<DiscreteMath`RSolve` use only upper- or only lowercase Letters for the same function, use brackets, not braces, use == for equations, = to assign values. RSolve[y[t+2]-2*y[t+1]+3*y[1]==4,y[t],t] you should learn how to use rules. Have fun, Peter