Re: log-depth-axis contour plot

[verschel@xxxxxxxxxxxxxxxxxxxxx (Mark A. Verschell)]

Patrick sent me a sample .jnl to generate this error, and after playing around
with it for a while, the best answer I can come up with is that ferret
(actually pplus that is a layer below ferret) cannot handle reverse log-axis
(e.g. depth).

The only work around I can come up with is (sketchy explanation here):
1) Save your data in reverse z, i.e., upside down from how you would normally
store it.
2) Plot the data with a logarithmic depth axis, but with no labels and no tic
marks on the depth axis.
3) It shouldn't be too difficult to design a simple .jnl file to use labels and
aline to place the appropriate tics and axis labels to simulate a depth
log-axis.

Hope this helps, if I have a spare moment, I will try to work this up and post
it back here.

Mark

On Aug 2,  3:59pm, Patrick Joeckel wrote:
> Subject: log-depth-axis contour plot
> Dear Ferret Users,
>
> On Fri, 19 Feb 1999 13:38:47 +0100 (MET)
> Rodrigo Caballero Augi gave the following example to do log-log contour
> plots and achieve a proper log-axis, i.e.
> 'the contours rescaled to the log axes *and* the "ppl axtype 2,2"-style
> tic marks - that is, with the ticks unevenly spaced'.
>
> However, if I try this with a /DEPTH-defined axis,
> ferret exits with this messages :
> YLO,YHI                                   on DEC-Alpha (Version 5)
>
> STOP: YLO,YHI
> Warning: Floating underflow occurred      on a Linux-PC (Version 5)
>
> Does anybody have a solution ?
>
> Thank you for your help !
>
> Sincerely,
>
>                Patrick Joeckel
>
>
> here is the above cited suggestion for non /DEPTH-defined axes:
> !!!!!!
>  ! 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
>  define grid/x=xax/y=yax gg
>  set grid gg
>  let a = LOG(x/10)+y/100    ! some made up data
>
>  ! plot untransformed data in the upper plot
>  set view upper
>  ppl axtype 1,1
>  contour a
>
>  ! define a new axis with the LOG transform of the X coordinates
>  define axis/from/name=xlog/x LOG(x)
>
>  ! plot LOG-transformed data in the lower plot
>  set view lower
>  ppl axtype 2,1
>  contour a[gx=xlog@asn]*0
>  ppl axtype 1,1
>  contour/over/pen=1/nolab a[gx=xlog@asn]
> !!!! end of example
>
> ---------------------------------------------------------------
> 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
> ---------------------------------------------------------------
>-- End of excerpt from Patrick Joeckel




-- 
 Mark Verschell                     NASA/Goddard Space Flight Center
 verschell@neptune.gsfc.nasa.gov    Code 970/Lab. for Hydrospheric Proc.
 301-614-5669  Fax: 301-614-5666    Greenbelt, MD 20771


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