Re: [Newbie] Interpreting output

*To*: mathgroup at smc.vnet.net*Subject*: [mg56654] Re: [Newbie] Interpreting output*From*: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>*Date*: Mon, 2 May 2005 01:32:37 -0400 (EDT)*Organization*: Uni Leipzig*References*: <d51nl8$cu9$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, f[x_] := Piecewise[{{x^2, x > c}, {x, x <= c}}] and D[f[x],x] gives Piecewise[{{2*x, c - x < 0}, {1, c - x >= 0}}, 0] as expected Regards Jens "MC" <daemmerung at enttaeuschung.com> schrieb im Newsbeitrag news:d51nl8$cu9$1 at smc.vnet.net... > Hi everybody.... > > I'm having troubles in interpreting the output > of Mathematica. > > My problem is to define a function F(x,y,z) such > that: > F = (whatever) if x>c > F=(whatever) if x<=c > > I achievied this using /; > > When I derive F with respect to one of the > variables, the result is a mess. > Just an example with 1 variable: > > f=x/;x>0; > f=-x^2/;x<0; > > D[f,x]=-2Condition(1,0)[x^2,x<0]+Condition(1,0)[x^2,x<0]Less(1,0)[x,0] > > Even in this very simple case, the result is a > real mess: > I really do not know how should I read > that...and I'm wondering if > I have defined the function in the right way. > > Anybody so kind to explain me what's goung on? > > Thank you very much for your patience > > >