Hi there,

I'm using gnuplot 3.6beta338 at the moment and have encountered a problem

using a datafile w/ splot:

The data is saved as z values (one line per value w/ a blank line separating

the rows or datalines in gnuplot terminology). It is a rectangular grid of

values.

I want to adjust the scaling on the splot so that the x and y axes show the

correct values instead of row and column numbers.

One method to do this is to use 'using' to rescale x and y. But there seems

to be two hurdles to overcome:

1) with 'using', there are three additional column numbers defined -

0,-1,-2. The help says 'using 1' is equivalent to 'using 0:-1:1'

but this is untrue (just try it).

Column zero is defined as a point counter which is reset on double blank

lines (or with a new index). It would be handy to have column 0 defined

as a point counter that is reset on single blank lines then the help

notes would be correct.

2) the $ notation can not cope with negative integers.

So as a workaround I have to use the following to rescale a 30 by 30 grid of

data values to the ranges [0:1] & [0:360]

splot 'data' index 1 using ($0/30.0 - int($0/30.0)):(column(-1)*12.0):1

Looking at the source, datafile.c line 119 indicates column number 0 should

reset at blank lines _not_ double blank lines. Perhaps you should add

df_datum = -1;

to line 937 in df_readline(), to solve the first point. The second point

I've tried looking at but the scanner code defeats my casual inspection.

Could any gnuplot developer comment on this and suggest fixes or patches?

TIA

Peter

--

Email to etzpc(at)unix.ccc.nottingham.NOSPAM.ac.uk