Network Working Group                                         W. ParrishRequest for Comments: 525                                     J. PickensNIC: 17161                           Computer Systems Laboratory -- UCSB                                                             1 June 1973                      MIT-MATHLAB MEETS UCSB-OLS:                     An Example of Resource SharingI. 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 resourcesParrish & Pickins                                               [Page 1]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.Parrish & Pickins                                               [Page 2]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>).Parrish & Pickins                                               [Page 3]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.Parrish & Pickins                                               [Page 4]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