SPECPLOT: y spacing for binary phases

Frank Valdes wrote on Oct 13, 1998

Q:  I have approximately 50 spectra that I would like to show using a specplot
type of multiplot.  That is, I would like to put them all on the same
graph.  They are of a binary and I would like to plot them such that the
interval between two successive graphs is related to the phase of the 
graph, which is a value I have placed in the header of the image.  I have
looked through splot and specplot documentation and it is not clear how
to do this in any method, with the possible exception of brute forcing it
after I have plotted them all and changing the offset and scale
interactively for all 50 spectra.  

Is there anyway to do it using splot or specplot or am I completely 
ignoring the better package to do it with.


A:  Actually you are the first person that has asked about phase spacing of
stacked plots.  It should be possible to automate this.  You can either
do it by modifying the intensities in the plot or using an @file or
header keyword for the "offset" parameter.  What you do depends on
whether the spectra have basically the same intensities.  If not you
might continuum normalize using CONTINUUM.  This can be done
non-interactively.  You could use a legendre function of order 1 to
simply normalize by a constant so that the continuum shape is not
removed.  Or maybe you would want the continuum to removed.  Once the
data have the same scale you could create a header keyword giving an
offset based on the phase.  If the phase is 0-1 then this could be done
with the command

cl> hedit <spectra> offset '(phase*10.12)' add+ update+ verify- show+

where you would put a value for the 10.12 that gets the spacing you want.
This command does some computations with header keywords and constants
to create the new value. Then in SPECPLOT do the plotting with "offset=offset".

I've not done any of this but the features you would try to use are
that the scale and offset parameters in SPECPLOT can be taken from header
keywords or a file of values (an @file).

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Last post on Oct 13, 1998