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 features: 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 viewdata.run. 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