USAGE:
 
   plot-vcvf [-ps <ps-file>] [i1[,i2,...] [j1[,j2,...] <vcvf-file>
   plot-vcvf [-ps <ps-file>] all [j1[,j2,...] <vcvf-file>
 
 PURPOSE:
   Plots excerpts of the variance-covariance matrix produced by urtapt
   on unit 15 under  qout_vcv_bin=.false. The result is a colour-coded
   grid, negative covariance in blue, positive in red nuances, each
   on a logarithmic scale.

   plot-vcvf all all <vcvf-file> is principally possible, but the paper
   geometry prohibits full display. For clarity, the channel reported
   on the y-axis would always contain a thematic selection.
   Custom sets of parameters are specified as the last-but-two and last-but-one
   arguments, channel numbers separated by commas, for the x- and the y-axis,
   respectively. Use the result sheet (prl-file) of the generating run of urtapt
   for selection. Tide parameters' real and imag parts must be addressed
   one-by-one.
 
   The plot title is at least the basename of the vcvf-file
   Whether the vcvf-file contains covariance or correlation depends on the
   parameter in urtapt,  qout_vcv_corr=.true. or .false.
 
 OPTIONS:
   -ps <ps-file> - default derived from vcvf-file name.
   -P            - output directory for PNG-file. Default ~/www/4me/toe/
   -title "text" - Adds "text" to title. Repeatable. Position on command line may
                     interleave "text" with what -corr or -cov has rendered.  
   -corr         - Adds "parameter correlation" to title, sets variable name to "Corr"
   -cov          - Adds "parameter covariance"  to title, sets variable name to "Cov"
                   Somewhat heuristic.
   -zfloor z     - The floor for the z-range, default is 0.001
   -size s       - Plot size for -Jx , default is 0.12
   -chs s        - Character size for text labels, default is 8
   -X xloc       - The -Xxloc option to psbasemap
   -u <name>     - For title, instead of the potentially clumsy vcv-file name
   -ft <table>   - Explain symbols using a feature table
 
 PURPOSE:
   excerpt of a VCV array, input from an ascii file
   (urtapt namelist qout_vcv_bin=.false., file unit 15)
 
 EXAMPLES:

   Abs.Grav Super-campaign:
 
      plot-vcvf -zfloor 0.01 -ps urtap-merged-O-sdr-lap-vcv.ps          \
                -size   0.36 -chs 12                                    \
                -P  ~/www/4me/ag-superc/                                \
                -ft t/feature-O-sdr.tbl                                 \
                -corr 1,2,3,4,5,82,83,84,85,86,87                       \
                      1,2,3,4,5,82,83,84,85,86,87                       \
                t/urtap-merged-O-sdr-lap.vcvf
 
   Tide analysis:
      plot-vcvf -X 3.5 -zfloor 0.01 -ps urtap-wspl-ochy-vcv.ps   \
                -size 0.36 -chs 12 -P ~/www/4me/toe/             \
                -u "Extended analysis,"                          \
                -corr `fromto -, 99 109` `fromto -, 99 109`      \
                tt/urtap-${URTAPFD}-wspl-ochy.vcvf

  
      plot-vcvf -X 3.5 -zfloor 0.01 -ps urtap-ochy-vcv.ps               \
                -size 0.36 -chs 12 -P ~/www/4me/toe/                    \
                -u "Extended analysis,"                                 \
                -corr 71,72,73,74,75,76,77 71,72,73,74,75,76,77         \
                tt/urtap-${URTAPFD}-ochy.vcvf

      plot-vcvf -ps vcv-corr-urtap-lap-ochy.ps all 71,72,74,76,78       \
                tt/urtap-lap-ochy.vcvf

   PNG result in:
       http://holt.oso.chalmers.se/hgs/4me/toe/vcvf-corr-urtap-lap-ochy.png

   with PAPER_MEDIA = a3 in .gmtdefaults4:
 plot-vcvf -zfloor 0.01 -ps urtap-merged-OO-ndr-fsg-S-ochy1d-nosl.ps  \
           -size 0.3 -chs 12  -P ~/www/4me/ag-superc/                 \
           -ft t/feature-OO-ndr-fsg-S.tbl                             \
           -corr `NR -, 1 8`,`NR -, 81 87`  `NR -, 1 8`,`NR -, 81 87` \
           t/urtap-merged-OO-ndr-fsg-S-ochy1d.vcvf

 plot-vcvf -zfloor 0.002 -ps urtap-merged-OO-ndr-fsg-S-ochy1d.ps          \
           -size 0.075 -chs 6 -P ~/www/4me/ag-superc/                     \
           -ft t/feature-OO-ndr-fsg-S.tbl -corr `NR -, 1 87` `NR -, 1 87` \
           t/urtap-merged-OO-ndr-fsg-S-ochy1d.vcvf