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RE: Define a function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg34567] RE: [mg34556] Define a function
  • From: "Annetts, Dave (E&M, North Ryde)" <David.Annetts at csiro.au>
  • Date: Wed, 29 May 2002 02:44:06 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Hi Michael,

> I want to define a function in Mathematica. But just 
> f[x_]:=...  does not
> work, because I have to define different functions for 
> different ranges of
> the variable x.
> For example:
> 
> x < 10:           f(x) = 0
> 10 < x < 20:  f(x) = x
> 20 < x:          f(x) = x/2
> 
> How to do this?

What about the value of f at 10 & 20?

In any case, something like ...

f1[x_] := 0 /; x < 10;
f1[x_] := x /; (10 <= x < 20);
f1[x_] := x/2 /; x >= 20;

should work.

You can also try using nested If[...]'s, Which[...] or Switch ....

Regards,

Dave.
--------------------------------------------------------
  Dr. David Annetts             EM Modelling Analyst
  Tel: (+612) 9490 5416         CSIRO DEM, North Ryde
  Fax: (+612) 9490 5467         David.Annetts at csiro.au
                 Include "usual_disclaimers"
--------------------------------------------------------


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