Re: Re: A plot of Sign[x]
- To: mathgroup at smc.vnet.net
- Subject: [mg94155] Re: [mg94146] Re: A plot of Sign[x]
- From: "Curtis F. Osterhoudt" <cfo at lanl.gov>
- Date: Sat, 6 Dec 2008 06:13:18 -0500 (EST)
- References: <gh8hjr$r0h$1@smc.vnet.net>
- Reply-to: cfo at lanl.gov
It's a sampling issue. Why not use a ListPlot of the exact numbers you want?
ListPlot[{#, Sign[#]} & /@ Range[-5, 5, 1/10]]
At least then you're guaranteed to sample right on zero. Your Table
example does exactly the same thing, but due to numerical problems, it
might not sample at exactly 1/100 intervals. Change the 0.01 to 1/100, and
you're guaranteed your Sign[0] == 0 point.
> Thanks for the replies.
>
> But do I really have to conclude that Mathematica is unable to make a
> decent
> automatic Plot of a function as simple as Sign[x]?
>
> Following does the trick:
> a := Table[{x, Sign[x]}, {x, -5, 5, .01}]
> ListPlot[a]
>
>
> Bert Aerts (rm X) wrote:
>
>> I tried to plot the Sign function, making clear that Sign[0]=0 by typing
>> Plot[Sign[x], {x, -5, 5}, Mesh -> 51, PlotRange -> All]
>> Making Mesh an odd value shows x=0.
>>
>> But the point at x=0 is being plot as 0.5 in stead of zero.
>>
>> What am I doing wrong?
>>
>> Mathematica 6.0.3 Linux x86_64
>
>
>