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MathGroup Archive 2002

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RE: Difference /recurrence equations

  • To: mathgroup at smc.vnet.net
  • Subject: [mg35141] RE: [mg35127] Difference /recurrence equations
  • From: "DrBob" <majort at cox-internet.com>
  • Date: Tue, 25 Jun 2002 19:55:38 -0400 (EDT)
  • Reply-to: <drbob at bigfoot.com>
  • Sender: owner-wri-mathgroup at wolfram.com

The following line:

y(t+2) - 2Y(t+1) + 3Y(1) = 4

should be:

y[t+2] - 2y[t+1] + 3y[1] == 4

Parentheses are NOT used for function notation in Mathematica, and "="
causes its left operand to be Set.  You also mixed small and capital Y
in that line -- they're two different symbols.

Bobby Treat

-----Original Message-----
From: Andrew Biggs [mailto:agbiggs at hotmail.com] 
To: mathgroup at smc.vnet.net
Subject: [mg35141] [mg35127] Difference /recurrence equations

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





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