# Re: log contour intervals

```Hello Alice,

unfortunately there is no direct solution. I had the same problem some
time ago. Here I forward the answer I got via the mailing list.
It contains an example that works also with the z-axis.

Hope it helps !
Best regards ...

Patrick

---------------- forwarded message -----------------------------------------
Hi Patrick,

Here is a more general technique that gives you full control over all
details of the axis labelling. I believe that it will work on Z axes, as
well.

- steve

===========================

! suppose you have some data on a grid x=1:100:1, y=1:100:1
define axis/x=1:100:1 xax
define axis/y=1:100:1 yax
let/title="test data" a = LOG(x[gx=xax]/8)+y[gy=yax]/100    ! some made up
data

! plot untransformed data
contour a

! define a new axis with the LOG transform of the X coordinates
define axis/from/name=xlog/x LOG(x[gx=xax])

! plot quick and dirty LOG-transformed data  in the upper plot
! NOTE: X axis labels will be LOG values rather than exponents
set window/new
set view upper
contour a[gx=xlog@asn]

! *** here's how to do a nicely labelled plot ***
set view lower

! base plot with large tics, only, unlabelled
ppl axlabp 0
contour/xlimits=0:2:1/title=" " a[gx=xlog@asn]

repeat/j=1:2:1 (repeat/i=1:10:1 ppl aline 1,`LOG(i)+j-1`,0,`LOG(i)+j-1`,-4)

! label the major tics with powers of 10
repeat/j=1:3:1 label `j-1`,-18,0,0,.1 "@SR10^`j-1`"

! label 2,3,5 of the minor tics
repeat/j=1:2:1 label `LOG(2)+j-1`,-15,0,0,.08 "@SR2"
repeat/j=1:2:1 label `LOG(3)+j-1`,-15,0,0,.08 "@SR3"
repeat/j=1:2:1 label `LOG(5)+j-1`,-15,0,0,.08 "@SR5"

============================
---- end of forwarded message -----------------------------------------------

---------------------------------------------------------------
Patrick Joeckel
Max Planck Institute for Chemistry
Joh.-J. Becher Weg 27
55128 Mainz                   phone:++49-6131-305452
Germany                       fax  :++49-6131-305436
e-mail:joeckel@mpch-mainz.mpg.de
http://www.mpch-mainz.mpg.de/~joeckel
---------------------------------------------------------------

```