Strange behaviour of arrow rto in logarithmic scale

[Harald H. <h.h...@tu...>]

When thinking of relative coordinates, I have found a strange behaviour of
`set arrow' when using `rto' in conjunction with logarithmic coordinates.

Have a look at the output of the following example:

# --------------------------------------------------------------
set logscale x
set logscale x2
set xrange [1:100]
set yrange [-1:1]
set x2range [1:100]
set y2range [-1:1]

set arrow from first 10,-0.3 rto first 5,0
set arrow from second 10,-0.1 rto second 5,0
set arrow from first 10,0.1 rto second 5,0
set arrow from second 10,0.3 rto first 5,0

set label ' first rto first ' at 10,-0.3 right
set label ' second rto second ' at 10,-0.1 right
set label ' first rto second ' at 10,0.1 right
set label ' second rto first ' at 10,0.3 right

plot 1/0 notitle

pause -1
# --------------------------------------------------------------

I am using two coordinate systems `first' and `second' with the same
ranges. When using the same coordinates for the start point and the
relative end point the end point is calculated by summating:
endpos =3D startpos + difference. If I, instead, change the coordinate
system between start point and relative end point, the `difference' is
taken as factor: endpos =3D startpos * difference.
Thus, for the cases `first to first' and `second to second', the arrows
end at 10+5=3D15 while for the cases `first to second' and `second to
first', they end at 10*5=3D50.

I think, this really should be consistent. And in order to allow also the
other changes, e.g., `screen to first', I think the usage as a factor is
better than the difference. Interpreting the offset as factor whould also
enable text offsets more easily.

What do you think?

Yours
Harald

P.S. I have not posted this as bug to sourceforge since I think here is
some discussion necessary.

--=20
Harald Harders                           Langer Kamp 8
Technische Universit=E4t Braunschweig      D-38106 Braunschweig
Institut f=FCr Werkstoffe                  Germany
E-Mail: h.h...@tu...               Tel: +49 (5 31) 3 91-3062
WWW   : http://www.ifw.tu-bs.de          Fax: +49 (5 31) 3 91-3058