This PC-based example is by no means indicative of the extent of the DESL capabilities. It is meant only as a flavor for the use of DESL. The system in general, each command and each command's set of options are fully explained in the HTML documentation which is provided as a part of the DESL download.

1. First, Excel data for "run = 10" are selectively exported to a tab-separated ASCII form - a "tsv" file. The example assumes there is a similar "run 11" file also exported to this form.
   

2. Once the tsv files exist, they are translated to SIF files , the form needed by the rest of the DESL commands. The two new files are named "run10" and "run11", respectively.
   

   In the above use of the translate command two files (r10.tsv r11.tsv) were specified and two new files (run10, run11) were named. Also, the origin file type was specified using the from option (two files at type = tsv) and the destination file type was indicated using inclusive the allto option (two new files at type = sif).

3. Once the two SIF files exist, they are used as input to the DESL stack command. The file "run11" is in effect appended to the file "run10". The resulting new SIF file contains the data corresponding to both files. The noappend option indicates that stack should NOT just blindly add the contents of "run11" to "run10". Rather, it should not keep the superfluous sets of variable names which would exist as having been drawn in from "run11".
   

4. Once the stacked SIF file (stak_10_11) exists, it is used as input to the DESL fit command. The fit command extracts the data corresponding to the global condition run = 10 and performs a third order piecewise polynomial fit of the dependent variables CL, CD, CMS and RUN for the values -2.0 -1.5 -1.0 -.5 0. .5 1.0 1.5 2.0 of the independent variable , ALPHA. RUN is also named as a dependent variable just to keep it in the new files. (There are also other ways to do this.)

   The tol option is used to force non-consideration (in the fit calculations) of a value in the ordered set of independent ALPHA values where a successive value would have been closer than .2 from the preceeding value. Wild fluctuations in some incoming data could cause wiggles in the calculated (fit) values of the dependent variables.

   

5. Finally, a plot of the resulting fit data -vs- the original data for run = 10 is plotted as two separate curves.

   The following DESL session indicates that the data in files run10 and fit_stack will be used for the first and second curves, respectively. The conditional requirement imposed on the first data set (file), indicated by the cset 1 run eq 10 specification, is present to filter the incoming data from the first file such that only the data corresponding to RUN = 10 is retained for plotting.

   The x-axis variable is indicated to be ALPHA and the y-axis variable is CL. Each curve could have been associated with any variable on the file, independently of one another.

   The pubplot options and option arguments specified in this example are fairly straightforward. The type of symbol, line and line/symbol color is specified, along with the 2-axis autoscaling option auto.

   

   The resulting PostScript plot, as rendered by Ghostview, is :

   

   A plot can be much more complex than this : it can be multi-plot per page, multi-page, and/or contain different types of plots : contour plots and surface plots, each with its own set of options such that the extent to which the user wishes to control the layout (appearance) and data representation is very flexible.

   In general, the simplest pubplot input that is possible is :

   pubplot
     files run10
     x alpha
     y cl
     quick
     plot
     go
   

   where the quick option implies many other options and arguments such that the resulting plot is fairly well laid out and defined.

   One of the strong features of DESL is its capability to run in a batch mode. It is entirely possible to use a set of DESL input specifications to cause the system to cycle through a long series of instructions producing plots during each cycle for a completely hands-off operation.

Contact the DESL manager

ViGYAN, Inc.

30 Research Drive Hampton, VA 23666 Voice: (757) 865-1400 Toll Free: (800) 288-3998 FAX: (757) 865-8177

© 1999 ViGYAN, Inc.