Network Working Group                                         W. Parrish
Request for Comments: 525                                     J. Pickens
NIC: 17161                           Computer Systems Laboratory -- UCSB
                                                             1 June 1973


                      MIT-MATHLAB MEETS UCSB-OLS:
                     An Example of Resource Sharing

I. Introduction

   A. Resource Sharing, A Comment

      Non-trivial resource sharing among dissimilar system is a much
      discussed concept which, to date, has seen only a few real
      applications.  [See NIC 13538, "1972 Summary of Research
      Activities (UTAH) for description of Tony Hearn's TENEX-CCN
      Programming Link.]  The first attempts have utilized the most
      easily accessible communication paths, (TELNET and RJS) and the
      most universal representations of numbers (byte-oriented numeric
      characters in scientific notation).  Future schemes will probably
      be more efficient through standardized data and control protocols,
      but even with the existing approaches users are gaining experience
      with combinations of resources previously not available.

   B. The MATHLAB/UCSB-OLS Experiment

      MATHLAB [1] and OLS are powerful mathematics systems which cover
      essentially non-intersecting areas of mathematical endeavor.
      MATHLAB (or MACSYMA) contains a high-powered symbolic manipulation
      system.  OLS is a highly interactive numeric and graphics system
      which, through user programs, allows rapid formulation and
      evaluation of problem solutions.  Prior to this experiment, users
      have dealt with problems symbolically on MATHLAB or numerically
      and graphically on OLS.  Lacking an interconnecting data path,
      users have been left to pencil and paper translation between the
      two systems.

      The goal of the MATHLAB-OLS experiment is to provide an automated
      path whereby expressions at MATHLAB may be translated into User
      Programs at UCSB.  Thus the user is able to experiment freely with
      the numeric, graphic, and symbolic aspects of mathematic problems.

II.  THE RESOURCES

   To understand this particular case of resource sharing, it is first
   necessary to understand, to some degree, the resources being shared.
   This paper does not attempt to deal with all of the resources



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RFC 525                MIT-MATHLAB MEETS UCSB-OLS            1 June 1973


   available at both sites (UCSB and MIT).  Only the applicable shared
   resources are discussed briefly.  In the section discussing
   possibilities for additions (Section V) some available unshared
   resources are presented, along with their possible shared
   applications.  The current implementation is limited to evaluation of
   real functions.  A description of the capabilities at the two sites
   follows.

   A. Graphical and Numeric Computation Capabilities at UCSB

      To get a graph of a function on the OLS, it is necessary only to
      specify the function with a series of button-pushes.  For example,
      to get a plot on sin(x), the "program"

              II REAL SIN x DISPLAY RETURN

      will display a plot of sin(x) versus X, provided that X has been
      defined as a vector containing values over the range which it is
      desired to plot.  For a more complete description of OLS see NIC
      5748, "The OLS User's Manual".  Programs in OLS, or sequences of
      button-pushes can be stored under USER level keys, i.e. the above
      program could be defined as USER LI (+) [2], and the user could
      display, modify, and look at various values of the SIN function
      over different ranges by simply setting up the desired value of
      the the vector X, and then typing USER LI (+).  The number of
      elements in such a vector is variable, up to a maximum of 873
      (default value is 51).  The vector containing the result can be
      stored under a letter key, i.e. Y, and can be looked at by typing
      DISPLAY Y.

      Scaling of plots on the OLS is automatic for best fit, or can be
      controlled.  Upon default, however, it is often desirable to look
      at plots of several functions on a common scale.  This can be done
      on the OLS, and the graphs will be overlayed.  OLS graphical
      capabilities are available to users at UCSB on the Culler-Fried
      terminals, and to Network users using a special graphics socket at
      UCSB.  See NIC 15747, RFC 503 "Socket Number List".  For Network
      users without Culler-Fried keyboards, see NIC 7546, RFC 216
      "TELNET Access to UCSB's On-Line System".

   B. Symbolic Manipulations Available at MATHLAB

      MATHLAB'S MACSYMA provides the capability to do many symbolic
      manipulations in a very straightforward and easy-to-learn manner.
      Included in these manipulations are:

         1) Symbolic integration and differentiation of certain
            functions.



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RFC 525                MIT-MATHLAB MEETS UCSB-OLS            1 June 1973


         2) Solutions to equations and systems of equations.

         3) Laplace and inverse-Laplace transforms of certain functions

         4) Certain series expansions.

         5) Rational simplification of rational functions.

   For a more complete description, see "The MACSYMA User's Manual" by
   the MATHLAB Group at Project MAC-MIT.

III.  A DESCRIPTION OF THE CURRENT IMPLEMENTATION

   A variety of programs are used to make up a system to effect this
   transfer of data.

      1) Two functions are defined in Lisp-like language which are
         loaded into MACSYMA after login in order to facilitate saving a
         list of expressions to retrieve later to UCSB, and to write
         this list out to a disk file at MATHLAB for later retrieval.

      2) A set of OLS user programs create the batch job which actually
         performs the retrieval, translation, and storage of these
         expressions on a specified file on some OLS user directory.

      3) The program which actually performs the connection to MATHLAB
         retrieves the expressions, translates and stores into the OLS
         is written in PL/1 and exists as a load module on disk at UCSB.

   The sequence of operations required in order to retrieve expressions
   using these various programs is outlined below:

      1) The user makes a connection to MIT-MATHLAB in the conventional
         manner.  This can be done either through UCSB-OLS, or through
         other TELNET programs, or from a TIP.

      2) The user logs in at MATHLAB, calls up MACSYMA, and loads the
         file into the MACSYMA system which facilitates retrieval.
         (Contains ADDLIST and SAVE functions.)

      3) The user performs the desired manipulations at MATHLAB, and
         saves up a list of line numbers as he goes along using the
         ADDLIST function.  These line numbers represent those
         expressions he wishes to retrieve.  The format for ADDLIST is
         ADDLIST('<LINE NUMBER>).






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RFC 525                MIT-MATHLAB MEETS UCSB-OLS            1 June 1973


      4) When the user has completed all the manipulations he wishes to
         do he saves them on the MIT-MATHLAB disk. (Using SAVE
         function.) The format for SAVE function is SAVE(<filename 1>).
         This function writes out, in horizontal form, the list of line
         numbers in the order the ADDLIST function was invoked to the
         MIT disk.  The filename will be <filename 1>BATCH.  SAVE also
         appends a question mark on the end of the file as an end-of-
         file indicator.

      5) USER disconnect from MATHLAB.

      6) User connects to and logs into OLS, and loads a file containing
         the user programs which produce a virtual job deck for the
         batch system.  A sequence of questions are given to the user by
         these programs regarding accounting information, and the source
         file at MIT, and the destination file at at UCSB.  The batch
         job gets submitted automatically, and the transfer and
         translation is done.

      7) After the transfer is completed, the destination file may be
         loaded into OLS, and the results may be displayed and numerical
         manipulations can take place.

   The form of these user programs, as they are returned is as follows:

         LII REAL LOAD (  function  )

   Therefore in order to look at a graph of one of these functions, it
   is necessary to set up values of various constants, as well as a
   range of values of the independent variable.  It is also necessary to
   request a display of the function.  This can be done by typing
   DISPLAY RETURN.  It should be noted that the function does exist at
   the time directly after the user program is called and may be stored
   under any of the alphabetical keys on the OLS.  Storing several of
   these functions under alphabetical keys will allow them to be called
   up for plotting on a common scale.  For example, if the functions
   were stored under the keys A, B, and C, they could be displayed on a
   common scale by typing DISPLAY ABC RETURN.

IV.  LIMITATIONS

      A. The program as it stands can only transfer expressions.
         Equations or functions are not implemented.

      B. Variable and constant names at MIT can contain more than one
         letter, but the current implementation recognizes only one-
         letter variable names.




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RFC 525                MIT-MATHLAB MEETS UCSB-OLS            1 June 1973


      C. The program as it stands does not handle complex numbers.

      D. The user is subject to failures of three independent systems in
         order to complete the transfer: the UCSB 360/75, the Network,
         and the PDP-10 at MIT.  This has not proven to be a serious
         constraint.

      E. Software changes at either site can cause difficulties since
         the programs are written assuming that things won't change.
         Anyone who has ever had a program that works knows what system
         changes or intermittent glitches can do to foul things up.
         With two systems and a Network things are at least four times
         as difficult.  Thanks are due to Jeffrey Golden at PROJECT MAC
         for helping with ironing things out at MATHLAB, and the UCSB
         Computer Center for their patience with many I/O bound jobs.

V. POSSIBILITIES FOR ADDITIONS

      A. Recognition of complex numbers, possibly for use with LII
         COMPLEX on the OLS.

      B. Addition to translation tables of WMPTALK for recognition of
         SUM, COSH, SINH, INTEGRATE, DIFF, etc. (Often MATHLAB will not
         be able to perform an integral or derivative, in which case it