Re: (no subject)

[Hans-Bernhard B. <br...@ph...>]

On Fri, 29 Oct 2004 em...@ru... wrote:

> My thought (without having delved deeply into the source code, I must
> admit) is to give the user one more type of scale much like logscale
> which they can select.  

You're thinking too narrowly there.

What we need here is a broader approach at not just this particular
re-mapping idea, but the entire general concept of "translated axes".  So
far, gnuplot supports two such translations: identity and logarithm.  
Extending this to general mapping functions has been discussed in the past
(I think under a heading like "generalized log axes"), but AFAIK no
implementation has ever been attempted.

In principle, what is needed is a pair of functions, which are inverses of
each other, so gnuplot can map from data coordinates to 'plotted
coordinates' for placing things, and also from plotted coordinates back to
data coordinates for jobs like auto-ticking and mouse feedback.  The
mappings have to be monotonous, or all hell would break loose, and for
this feature to be more than an isolated special-purpose tool, the
mappings have to be specifiable as user-defined functions, e.g.

	set scale x1  sin(x1), asin(x1)

There's a ton of questions to be answered before this can be implemented,
mostly revolving about how to code an automatic range fix-up and automatic
tick placement algorithm that work somewhat robustly in such a generalized
situation.  As a first step towards that, we need a re-design of the
auto-ticking algorithm that makes them behave reasonably in the face of
short-range log axes.

For the time being, you'll just have to re-map coordinates on the go and
place xtics with 'faked' numbers, as demonstrated by earlier replies.

-- 
Hans-Bernhard Broeker (br...@ph...)
Even if all the snow were burnt, ashes would remain.