Next: , Previous: Lambda Calculus, Up: Top

6 Miscellaneous

— Command: %

The symbol % represents the last expression obtained by Jacal. It can be used in formulas like any other constant or variable or expression.

          e21: 5
          e22 : %;
          e22: 5
          e23 : %^2;
          e23: 25
— Command: batch filename

The command batch is used to read in a file containing programs written in Jacal. Here, filename is a string in double quotes. The precise way in which one refers to a file is, of course, system dependent.


of the file demo in the JACAL directory will give a demonstration of JACAL's capabilities.

— Command: tex expr
— Command: scheme expr
— Command: disp2d expr
— Command: standard expr

Displays expr in TeX, Jacal's two-dimensional output format, or Jacal's infix input format, respectively.

— Command: tex string

Read TeX expression string.

— Command: scheme string

Read Scheme expression string.

— Command: disp2d string
— Command: standard string

Reads string in Jacal's infix input format.

     e24 : b^2-4*a*c;
     e24: b  - 4 a c
     e25 : tex(e24);
     b^{2} - 4\,a\,c
     e25 : tex("b^{2} - 4\,a\,c");
     e25: b  - 4 a c
     e26 : disp2d(e25);
     b  - 4 a c
     e26 : disp2d("b^2-4*a*c");
     e26: b  - 4 a c
     e27 : scheme(e26);
     (- (^ b 2) (* 4 a c))
     e27 : scheme("(- (^ b 2) (* 4 a c))");
     e27: b  - 4 a c
— Command: commands

The command commands produces a list of all of the command available in Jacal. It is called as s function of no arguments.

e21 : commands();
% * + - / = ^ ^^ abs args augcoefmatrix b+/- b-/+ batch bunch cabs cartprod chain charpoly coeff coeffs coefmatrix cofactor col commands content continue crossproduct degree denom depends describe determinant diagmatrix diff differential discriminant disp2d divide dotproduct elementwise eliminate equatecoeffs example extrule factor factorial factors finv flatten func gcd genmatrix help ident imagpart interp interp.lagrange interp.neville interp.newton jacobi jacobian listofvars load matrix minor mod ncmult negate num or over parallel partial poly polydiff polyelim prime? qed quit rank rapply realpart require restart resultant row scalarmatrix scheme set shadow show standard sylvester system terms tex transcript transpose u+/- u-/+ verify wronski wronskian
— Command: describe command

The command describe is the heart of the online help facility of Jacal. Here, command is a string which is the name of a command and describe produces a brief description of the command and in many cases includes an example of its use. Together with the command commands(), which prints a list of all available Jacal commands, and the command example, which gives an example of the use of the command, one can in principle use Jacal without a manual after one has learned how to get started.

          e27 : describe(col);
          column.  column of a matrix
          e27 : describe(resultant);
          resultant.  The result of eliminating a variable between 2
          equations (or polynomials).
          27 : describe(+);
          Addition, plus.
          a + b
— Command: example command

Here, command is a string which is the name of a Jacal command. example gives an example of the use of the command. See also describe.

          e43 : example(+);
          a + b
          e43: a + b
— Command: load string

The Jacal command load takes as input a string and reads in a ‘Scheme’ file whose name is obtained by appending the extension .scm to the string. If you want to read in a file of Jacal commands, do not use load. Instead use the command batch. To load in the file foo.scm,

          e9 : load("foo");
          e9: foo
— Command: qed

Exit from Jacal to Scheme. With interactive Scheme systems (such as SCM), It does not return you to the operating system. Instead it suspends Jacal and returns you to the underlying scheme. You can return to the Jacal session where you left off by simply typing (math). If you do not wish to return to Jacal but really want to terminate the session and return to the operating system, then after typing qed();, type (slib:exit) or use quit. — Command: quit

Exit directly from Jacal to the operating system. You will not be able to continue your Jacal session.

          type qed(); to return to scheme
          e1 : qed();
          > (math)
          type qed(); to return to scheme
          e2 : quit();
— Command: system command

One can issue commands to the operating system without leaving Jacal. To do this, one uses the command system. For example, in a UNIX operating system, the command system("ls"); will print the directory. One way in which the command system might be especially useful is to edit files containing Jacal scripts without leaving Jacal, particularly in non-UNIX machines or on machines without GNU emacs.

          e0 : system("echo hi there");
          hi there
          e0: 0
— Command: terms

Prints a copy of the GNU General Public License

          e1 : terms();
                              GNU GENERAL PUBLIC LICENSE
                                 Version 3, 29 June 2007
           Copyright (C) 2007 Free Software Foundation, Inc. <>
           Everyone is permitted to copy and distribute verbatim copies
           of this license document, but changing it is not allowed.

[ rest deleted for brevity]

— Command: transcript string

The command transcript allows one to record a Jacal session. It is called with the syntax transcript(string);, where string is the name of the file in which one wants to keep the transcript of the session. When one wishes to stop recording, one types transcript();. One is then free to use transcript again later in the session on another file. One can use it on the same file, but the file is overwritten. Presently, the command transcript does not echo commands to a file.

          e9 : a:[1,2,3];
          e9: [1, 2, 3]
          e10 : transcript("foo");
          e10: foo
          e11 : a;
          e11: [1, 2, 3]
          e12 : transcript();
          e12 : system("cat foo");
          e10: foo
          e11 : a;
          e11: [1, 2, 3]
          e12 : transcript();
          e12: 0
— Command: set flag value

There are various flags that the Jacal user can control, namely the Jacal command line prompt, the priority for printing terms in Jacal output, the input grammar and the output grammar. For a discussion of the various grammars please See Flags. The command show is closely related, allowing one to see what the current settings are.

— Command: show flag

The command show enables the Jacal user to examine the current setting of various flags as well as to list the flags that can be set by the user and to display other information. To change the settings of the flags, use the command set. To see all the information accessible through the show command, type show all. To see the available grammars, type show grammars. To see the current input grammar type show ingrammar. To see the current output grammar, type show outgrammar. To see the current priority for printing expressions, type show priority.

e1 : show all;
all debug echogrammar grammars horner ingrammar linkradicals outgrammar page phases priority prompt trace version width
e1 : show prompt;

e1: e1

e3 : show priority;
:@ (differential :@) @3 @2 @1 y x wronskian wronski verify u-/+ u+/- transpose transcript tex terms t system sylvester standard show shadow set scheme scalarmatrix row resultant restart require realpart rapply rank quit qed prompt priority prime? polyelim polydiff poly partial parallel over or num negate ncmult mod minor matrix load listofvars jacobian jacobi interp.newton interp.neville interp.lagrange interp imagpart ident help genmatrix gcd func flatten finv factors factorial factor extrule example equatecoeffs eliminate elementwise e0 dotproduct divide disp2d discriminant differential diff diagmatrix determinant describe depends denom degree crossproduct continue content commands col cofactor coefmatrix coeffs coeff charpoly chain cartprod cabs c bunch batch b-/+ b+/- b augcoefmatrix args all abs a ^^ ^ ? = ::@ / - + * % %sqrt1 %i
e3 : show outgrammar;

e3: disp2d

e4 : show ingrammar;

e4: standard

e5 : show grammars;

e5: [scheme, null, schemepretty, standard, disp2d, tex]