PLOTAN, a generalized plot analysis routine written for the IBM 7094 computer, minimizes the difficulties in adding plot capabilities to large existing programs. PLOTAN is used in conjunction with a binary tape writing routine and has the ability to plot any variable on the intermediate binary tape as a function of any other

Harris, J. C.

Linnekin, J. S.

English

NASA Technical Reports Server

November 1966
	 Brief 66-10511 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Computer Routine Adds Plotting Capabilities to Existing Programs 
The problem: 
To devise an easy, flexible means of adding a plot-
ting capability to new or existing FORTRAN pro-
grams. Programmers often run into problems in try-
ing to adapt programs to provide specific plotting 
functions while working with a limited memory 
machine. 
The solution: 
PLOTAN, a generalized plot analysis routine writ-
ten for the IBM 7094 computer which minimizes the 
difficulties in adding plot capabilities to large existing 
programs. PLOTAN is used in conjunction with a 
binary tape writing routine, WRITER, which pro-
duces an intermediate binary tape. PLOTAN then 
edits this tape and produces a new tape which may be 
plotted off-line on the CALCOMP 570 digital in-
cremental plotter. 
PLOTAN has the ability to plot any variable on 
the intermediate binary tape as a function of any 
other. Flexible input techniques or data and axis 
labeling minimize user programming changes and 
their associated costly recompilations. Since only 
425 8 storages are required in the user's program, a 
minimum sacrifice of storage is required. 
How it's done: 
For the user to generate the intermediate binary 
tape, he must compile into his program a statement of 
the following type: CALL WRITER (K, ICASE, A, 
M, NTAPE, N, MODE) where the variables in the 
calling sequence are controls for the routine 
(WRITER) which generates the intermediate binary 
tape. Each call to WRITER generates one logical 
record on the intermediate binary tape. This logical 
record consists of M physical records, where M is 
input to WRITER which is supplied by the user.
The logical record is composed of all the data which 
the user wishes to put on tape for a particular point. 
The user may save the intermediate binary tape and 
process it at a later time, or, by using the CHAIN 
feature of FORTRAN II, he may process the tape 
immediately after it has been generated. 
There are three distinct types of input to PLOTAN. 
The first of these is the intermediate binary tape con-
sisting of N logical records. Additional input is sup-
plied by subroutine KONST which is executed once 
per job and which defines input parameters or con-
stants that are required by PLOTAN, but seldom, if 
ever, change. This is accomplished by defining an 
array, S, of dimension (400) and placing it in common 
storage. Both BCD (Binary Coded Decimal) and 
floating point variables are carried in this way. The 
final input to PLOTAN is provided by subroutine 
OVERLAY which permits any variable in the S-array 
to be overlaid at the start of each case. This input is 
optional and is used to define or redefine any member 
of the S-array. Thus this subroutine reads all of the 
input data for PLOTAN that is not "built-in" by 
subroutine KONST. If all required S's are already 
defined in KONST, no additional input (other than 
blank cards) is required. 
Using these three inputs, the main routine, PLO-
TAN, edits the intermediate tape and the desired 
plotting information is written out on an input tape 
according to the very rigid format specifications re-
quired by the CALCOMP 570 plotter. This tape is 
then plotted by the CALCOMP off-line plotter. 
This routine includes the ability to plot any varia-
ble in the binary tape as a function of any other and 
also has the ability to modify labels and control vari-
ables by the use of the OVERLAY technique. In 
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19660000509 2020-03-11T17:44:09+00:00Z
addition, the program may be used independently to 
process the intermediate tape or as a second link of 
a CHAIN job. This eliminates the storage problems 
normally associated with the incorporation of plotting 
capability into a large routine. 
Notes: 
1. A report, entitled "PLOTAN, A Generalized Plot 
Analysis Routine for the 7094," by Jerry S. 
Linnekin and JoAnne C. Harris, X-513-65-344, 
August 1965, and published by Goddard Space 
Flight Center, Greenbelt, Maryland, contains a 
listing of the FORTRAN program, an explanation 
of its construction and use, and a number of sam-
ple plots obtained using the routine.
2. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Goddard Space Flight Center 
Greenbelt, Maryland 20771 
Reference: B66-10511 
Patent status: 
No patent action is contemplated by NASA. 
Source: Jerry S. Linnekin and JoAnne C. Harris 
of Litton Industries 
under contract to 
Goddard Space Flight Center 
(GSFC-490) 
Brief 66-10511	 Category 01


Computer routine adds plotting capabilities to existing programs

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