Re: [Gnuplot-info] Step function not starting at absolute 0

[Marek W. G. <gu...@if...>]

 > From: GOO Creations
 > To: gnu...@li...
 > Cc:
 > Date: 2014/8/25, Mon 16:07
 > Subject: [Gnuplot-info] Step function not starting at absolute 0
 >
 > Hi all,
 >
 > I'm trying to create a simple step function. I have this weird problem that
 > the x-values of my function do not start at absolute 0, therefore creating a
 > skew function. Here is my code:
 >
 >    /set xzeroaxis lc "black"//
 >    //set yzeroaxis lc "black"//
 >    //set terminal pdf//
 >    //set output "step.pdf"//
 >    //f(x)= x <= 0 ? -1 : 1//
 >    //plot f(x) lw 2 lc "black"//
 >    /
 >
 >
 > I've also attached the output PDF. As you can see the middle part of the
 > function is not parrallel with the y-axis. Does anyone know what I'm missing
 >
 > Chris

This is not strange because the sampling points in x axis is a finite number.
(default 100).
Increasing sample number like "set sample 1000", the appearance will be better but
that is the results mere approximation will be better.

Tatsuro



Here are my "two cents":

1. Original function has a jump at x=0.  Formally, nothing like vertical
line should be drawn at x=0.  The reason for "incorrect" drawing
has been already pointed by Tatsuro.

2. Correct solution is to define TWO functions:
f(x) = x<=0.0?-1.0:1/0
g(x)=x>0.0?1.0:1/0

and plot them both, say
plot [*:*][-1.1:1.1] f(x) lw 2 lc "black", g(x) lw 2 lc "black"

Now you have a plot which is indeed correct.

Cheers,
Marek Gutowski