       Re: Division by zero, despite strong hint

• To: mathgroup at smc.vnet.net
• Subject: [mg96576] Re: [mg96542] Division by zero, despite strong hint
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Mon, 16 Feb 2009 16:38:58 -0500 (EST)

```You left a comma out

g3[x_] := Piecewise[{{Sin[1/x], x != 0}, {0, x == 0}}]

Plot[g3[x], {x, 0, 1}, PlotStyle -> Red]

However, the second condition is unnecessary since the default is zero

g3[x_] := Piecewise[{{Sin[1/x], x != 0}}]

Plot[g3[x], {x, 0, 1}, PlotStyle -> Red]

Bob Hanlon

---- dch888 <dch888 at googlemail.com> wrote:

=============
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 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.

```

• Prev by Date: Re: Division by zero, despite strong hint
• Next by Date: Re: Re: Log[]//TraditionalForm
• Previous by thread: Re: Division by zero, despite strong hint
• Next by thread: Re: Division by zero, despite strong hint