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Re: restricting range?

• To: mathgroup at smc.vnet.net
• Subject: [mg57445] Re: [mg57429] restricting range?
• From: "David Park" <djmp at earthlink.net>
• Date: Sat, 28 May 2005 05:39:08 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

You could use the Assuming statement.

f[t_] := Which[t < 1/4, 1, True, t^2]

Assuming[t < 1/4, f[t] // Simplify]
1

In 5.1.1 the Piecewise function is probably more useful than defining with
the Which statement.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/

From: Ken Turkowski [mailto:turk at worldserver.com]
To: mathgroup at smc.vnet.net


I have a function that has multiple branches (using Which), but I would
like to restrict its evaluation to one branch for purposes of feeding
into Solve.

I tried
   f[t] /; t<1/4
and
   (t < 1/4) && f[t]
but neither works. I know I've seen something like this for square roots
in the Mathematica book,
   Sqrt[x^2] restricted to (Im[x] == 0) && (x >= 0)
but I can't find it. Can you help me?