ViewData -- 2D projections of 3D data on Display Screen

ViewData is a BCPL subsystem that will draw a picture of a file of data
on your  dispaly screen,  and allow you  to interactively  control your
point of view on the data.  It handles only a two-dimensional  array of
single-word values (i.e. a three-dimensional surface, a function of two
variables evaluated  over a regular  finite grid).  Here  is a  list of

   1) ViewData accepts input  in the simplest possible file  format: an
   optional header of any number of words (with any contents, which are
   ignored), followed by  a block of (signed)  data words of  any size,
   with any dimensions.

   2) ViewData  takes all parameters  from a dialog  with the  user via
   keyboard  and  mouse.   By  specifying  different  header  sizes and
   dimension  sizes, the  user can  exercise limited  control  over the
   selection of data from his file.

   3)  ViewData  takes  all  graphical  parameters  from  screen points
   clicked with the  mouse.  A point of  view is specified  by clicking
   the screen positions of three corners of the data array.  Zooming is
   accomplished by  clicking opposite  corners of  the rectangle  to be
   expanded.  Prompts  appear below  the plot  region to  indicate what
   points and/or switches to click.

   4) ViewData  contains a call  to DCBPress to  allow generation  of a
   one-page  output file  with a  picture of  your data.   This  can be
   annotated  by Markup  and printed  by an  appropriate  server.  With
   PressEdit, it can be editted into a report.

   5) ViewData uses the new PlotStream package (to be released soon) to
   provide  a display  interface which  is transparent  to  the average
   programmer; thus the program is easily modified to better  suit your
   data viewing requirements.

   6) ViewData is reasonably small, especially if one  deletes unneeded
   routines from the various files which are loaded with  it (MathUtil,
   SDialog, UtilStr, PlotStream, FractionProduct, DCBPress).

Getting and Running Viewdata:

Use FTP to  retreive  If you  need some sample  data, use
the FTP  Load command  to get Test.Data  from ViewData.Dm  (stored with
sources).  Execute ViewData and  default all the parameters with  CR to
get a sample display.  Using the mouse, follow the instructions  of the
prompts to zoom,  redraw in a new  orientation, or overview  (zoom back
out to  the highest  level).  After  you finish  by pressing  all three
mouse buttons at once, you have the options of producing a  press file,
restarting (possibly with a new data file), or quitting.

                   Copyright Xerox Corporation 1979