Re: Piecewise functions

*To*: mathgroup at smc.vnet.net*Subject*: [mg51573] Re: [mg51553] Piecewise functions*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Sat, 23 Oct 2004 00:22:03 -0400 (EDT)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*References*: <200410220222.WAA07319@smc.vnet.net>*Reply-to*: murray at math.umass.edu*Sender*: owner-wri-mathgroup at wolfram.com

You CAN do it without UnitStep if you really want: y[x_] := Which[x > 3, x, -1 < x < 3, -x, True, 1] Plot[y[x], {x, -5, 5}]; But you'll get the same spurious vertical line segment at x = 3 that you will if you do use UnitStep: y[x_]:=x UnitStep[x - 3] - x(-UnitStep[x - 3] + UnitStep[x + 1]) + (1 - UnitStep[x + 1] Plot[y[x], {x, -5, 5}]; Luca 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. -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305

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