Re: Adding unwrap to gnuplot

[Ethan A M. <sf...@us...>]

On Thursday, 30 January, 2014 17:30:32 Jon Gjengset wrote:
> > Have a look at the running average demo:
> > 
> >   http://gnuplot.sourceforge.net/demo_4.6/running_avg.html
> > 
> > Substituting an unwrap function for the avg5() function should do what
> > you want. It would not require any changes to the executable code.
> 
> Ah, yes, that should work nicely for now.
> 
> > One problem I see is that the resulting plot would not stable when
> > zoomed.  Each change in xrange would potentially shift the whole curve
> > on y by some multiple of 2π.
> 
> This would certainly be true for continuous functions, but for data you
> could potentially always unwrap the entire dataset and ignore the
> xrange.
> 
> I'm actually not entirely sure what you would expect as a user if you
> zoomed in a generated plot with unwrapping enabled...
> 
> > I don't think that adding a new function with a single argument is
> > what you want. It seems to me this is more like a trivial smoothing
> > operation, and the easiest fit into gnuplot's existing organization
> > would be
> 
> I agree, it does seem to fit more naturally as a smoothing operation. In
> fact, if you have phase data, that is exactly what it does.
> 
> > If you want to work on implementing this in the code, start by looking
> > in plot2d.c for switch statements that handle SMOOTH_NONE or its
> > alternatives.
> 
> I'll have a look.
> Is such a change something you would consider merging?

Yes.  
The actual smoothing code will probably only require a few lines of C.
The trickier part may be deciding whether or not it needs to be
reexecuted on replot/refresh/zoom/unzoom.

	Ethan