Re: Piecewise functions

*To*: mathgroup at smc.vnet.net*Subject*: [mg51561] Re: [mg51553] Piecewise functions*From*: DrBob <drbob at bigfoot.com>*Date*: Sat, 23 Oct 2004 00:21:41 -0400 (EDT)*References*: <200410220222.WAA07319@smc.vnet.net>*Reply-to*: drbob at bigfoot.com*Sender*: owner-wri-mathgroup at wolfram.com

Clear@y y[x_] /; x > 3 := x y[x_] /; -1 < x < 3 := -x y[_] := 1 Plot[y@x, {x, -2, 4}] y/@{-1,3} {1,1} or Clear@y y[x_] := Which[x > 3, x, -1 < x < 3, -x, True, 1] Plot[y@x, {x, -2, 4}] y/@{-1,3} {1,1} or Clear@y y[x_] := 1 + (-1 - x) UnitStep[x + 1] + 2x UnitStep[x - 3] Plot[y@x, {x, -2, 4}] y/@{-1,3} {1,3} The last form has big advantages if you want to differentiate or integrate the function. Bobby On Thu, 21 Oct 2004 22:22:10 -0400 (EDT), Luca <luca at nospam.it> wrote: > Hi all. I'm studying for the exam of signals and systems and I was > trying to plot some kind of functions I transformed for exercise. So, I > need to plot piecewise functions like: > > y(x) = x if x > 3 > y(x) = -x if -1 < x < 3 > y(x) = 1 else > > (should have been a system). > I found out in the guide the chapter about this, and I learned that it > is possible with the function UnitStep, which I know. Anyway, I found > it difficult to determine the equation of the function using this > method. Is it possible to do it simply writing everything like I did > before, more or less? i.e. without having to determine the equation > with the UnitStep function. > Hope I've been clear enought. Many thanks. > > Luca > > > > -- DrBob at bigfoot.com www.eclecticdreams.net

**References**:**Piecewise functions***From:*Luca <luca@nospam.it>