Re: Piecewise functions

*To*: mathgroup at smc.vnet.net*Subject*: [mg8953] Re: [mg8876] Piecewise functions*From*: Allan Hayes <hay at haystack.demon.co.uk>*Date*: Mon, 6 Oct 1997 01:59:21 -0400*Sender*: owner-wri-mathgroup at wolfram.com

Venkateswara Rao Ayyadevara <va2a+ at andrew.cmu.edu> mg8876] Piecewise functions > I would like to know how to represent piecewise linear functions in > Mathematica. I tried searching on-line help but could not find any > info regarding this. Venkat, In addition to the ways given by Stephen Luttrell in [mg8906] you might like to try the following. f[x_] := Which[ x<=0,-x,True,x]; This can be extended: ?Which "Which[test1, value1, test2, value2, ... ] evaluates each of the testi in turn, returning the value of the valuei corresponding to the first one that yields True." This and the Dirac function approach allow the function f to be differentiated by using f' or, for example, D[f[x],x]. This is not possible with case by case definition as g[x_]:=-x/;x\[LessEqual]0 g[x_]:=x/;x\[GreaterEqual]0 Allan Hayes hay at haystack.demon.co.uk http://www.haystack.demon.co.uk/training.html voice:+44 (0)116 2714198 fax: +44 (0)116 2718642 Leicester, UK