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.