Re: piecewise vs which

*To*: mathgroup at smc.vnet.net*Subject*: [mg60112] Re: [mg60101] piecewise vs which*From*: Chris Chiasson <chris.chiasson at gmail.com>*Date*: Sat, 3 Sep 2005 02:06:00 -0400 (EDT)*References*: <200509020833.EAA05912@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

The answer you seek is in the documentation for Piecewise. All Piecewise functions have a default value of zero on their undefined intervals. You can change this. On 9/2/05, Bradley Stoll <BradleyS at harker.org> wrote: > Consider defining a function in Mathematica (v. 5.2) in two different > ways: f[x_]=Piecewise[{{x^2,x<2},{3x,x>2}}] and > g[x_]=Which[x<2,x^2,x>2,3x]. Notice that 2 is not in the domain of > either function. However, if I ask for f[2], Mathematica returns 0 and if I ask > for g[2] Mathematica (correctly) returns nothing. Is this a bug with > Mathematica (that Mathematica returns 0 for f[2]), since 2 is not in the domain? > While I have eyes, there is another question regarding limits. Is it > the case that Limit[f[x],x->2] defaulted as > Limit[f[x],x->2,Direction->-1] (a right hand limit)? Both return 6 in > the above example. I'm using Mathematica in my calculus class and would > like to explain why Mathematica does certain things. It doesn't seem > that it would've been too difficult to just have two subroutines (a > right and left hand limit) to determine whether a 'full' limit actually > existed. > Thanks! > > Bradley > > -- Chris Chiasson http://chrischiasson.com/ 1 (810) 265-3161

**References**:**piecewise vs which***From:*"Bradley Stoll" <BradleyS@harker.org>