Re: Division by zero, despite strong hint

*To*: mathgroup at smc.vnet.net*Subject*: [mg96594] Re: [mg96542] Division by zero, despite strong hint*From*: "David Park" <djmpark at comcast.net>*Date*: Mon, 16 Feb 2009 16:42:15 -0500 (EST)*References*: <7722908.1234786522774.JavaMail.root@m02>

You left out a comma. g3[x_] := Piecewise[{{Sin[1/x], x != 0} , {0, x == 0}}] Plot[g3[x], {x, -.1, .1}] Help indicates that the routine evaluates the conditions first, without evaluating the expressions, and picks the first condition that is true. Also, it is possible in Plot that the value 0 was never used. David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ From: dch888 [mailto:dch888 at googlemail.com] Hi, I'm trying to plot the Sin[1/x] curve with the curve being defined as 0 at 0 like this: g3[x_] := Piecewise[{{Sin[1/x], x != 0} {0, x == 0}}] Invoking Plot produced a flat graph; puzzled I asked for g3[0] and got: Power::infy Infinite expression 1/0 encountered >> { {Indeterminate, False True}, {0, \!\(\* TagBox["True", "PiecewiseDefault", AutoDelete->False, DeletionWarning->True]\)} } Hmmm... what's the trick here to stop Mathematica evaluating all the branches of the piecewise fn? There's nothing in the documentation that I can see to stop this in Piecewise... perhaps I need to use a different Mathematica function? Thanks, David.