[Gnuplot-bugs] splot binary specification incorrect

[Zack S. <za...@fn...>]

I have been using gnuplot 3.7 patchlevel 3 on a linux system recently, but 
I see that this bug still exists in the v. 4.0 documentation and source 
code.

You specify that
> splot "filename" binary
will load a binary file of the format:
<N+1> y0  y1 ...  yN
 x0  z00 z01 ... z0N
 x1  z10 z11 ... z1N etc.

This is not correct.  The actual format appears to be:

<N>  x0  x1 ...  xN
y0  z00 z01 ... z0N
y1  z10 z11 ... z1N etc.

i.e. a) you should specify that the lines have N z-components, rather 
than being N+1 single-precision numbers long. b) the x and y axes are 
swapped vs. the specification.

If you use N+1 instead of N for your 1st entry, the file will not load.

You can confirm the second bug by creating a test file whose data values 
only change with y (or x), and look at the resulting plot.

A temporary fix for people who missed the axis-swapping is to just fix the 
first number to be <N> and use:
splot "filename" binary using ($2):($1):3

Please update the documentation to correct this.  If this is an unexpected 
correction, then I would request that you change the documented 
specification rather than alter the code, as binary data files are 
unpleasant to rewrite.

Aside: Note, that the example binary files are generated by outputting <N> 
as the first number.  Looking at the source code is how I finally 
identified the first bug.  Creating a simple test file is how I identified 
the second.

	Zack Sullivan
	Fermi National Accelerator Laboratory