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4.2 Functions and Variables for Command Line

System variable: __

__ is the input expression currently being evaluated. That is, while an input expression expr is being evaluated, __ is expr.

__ is assigned the input expression before the input is simplified or evaluated. However, the value of __ is simplified (but not evaluated) when it is displayed.

__ is recognized by batch and load. In a file processed by batch, __ has the same meaning as at the interactive prompt. In a file processed by load, __ is bound to the input expression most recently entered at the interactive prompt or in a batch file; __ is not bound to the input expressions in the file being processed. In particular, when load (filename) is called from the interactive prompt, __ is bound to load (filename) while the file is being processed.

See also _ and %.

Examples:

(%i1) print ("I was called as", __);
I was called as print(I was called as, __) 
(%o1)              print(I was called as, __)
(%i2) foo (__);
(%o2)                     foo(foo(__))
(%i3) g (x) := (print ("Current input expression =", __), 0);
(%o3) g(x) := (print("Current input expression =", __), 0)
(%i4) [aa : 1, bb : 2, cc : 3];
(%o4)                       [1, 2, 3]
(%i5) (aa + bb + cc)/(dd + ee + g(x));
                            cc + bb + aa
Current input expression = -------------- 
                           g(x) + ee + dd
                                6
(%o5)                        -------
                             ee + dd
Categories: Global variables ·
System variable: _

_ is the most recent input expression (e.g., %i1, %i2, %i3, …).

_ is assigned the input expression before the input is simplified or evaluated. However, the value of _ is simplified (but not evaluated) when it is displayed.

_ is recognized by batch and load. In a file processed by batch, _ has the same meaning as at the interactive prompt. In a file processed by load, _ is bound to the input expression most recently evaluated at the interactive prompt or in a batch file; _ is not bound to the input expressions in the file being processed.

See also __ and %.

Examples:

(%i1) 13 + 29;
(%o1)                          42
(%i2) :lisp $_
((MPLUS) 13 29)
(%i2) _;
(%o2)                          42
(%i3) sin (%pi/2);
(%o3)                           1
(%i4) :lisp $_
((%SIN) ((MQUOTIENT) $%PI 2))
(%i4) _;
(%o4)                           1
(%i5) a: 13$
(%i6) b: 29$
(%i7) a + b;
(%o7)                          42
(%i8) :lisp $_
((MPLUS) $A $B)
(%i8) _;
(%o8)                         b + a
(%i9) a + b;
(%o9)                          42
(%i10) ev (_);
(%o10)                         42
System variable: %

% is the output expression (e.g., %o1, %o2, %o3, …) most recently computed by Maxima, whether or not it was displayed.

% is recognized by batch and load. In a file processed by batch, % has the same meaning as at the interactive prompt. In a file processed by load, % is bound to the output expression most recently computed at the interactive prompt or in a batch file; % is not bound to output expressions in the file being processed.

See also _, %%, and %th.

System variable: %%

In compound statements, namely block, lambda, or (s_1, ..., s_n), %% is the value of the previous statement.

At the first statement in a compound statement, or outside of a compound statement, %% is undefined.

%% is recognized by batch and load, and it has the same meaning as at the interactive prompt.

See also %.

Examples:

The following two examples yield the same result.

(%i1) block (integrate (x^5, x), ev (%%, x=2) - ev (%%, x=1));
                               21
(%o1)                          --
                               2
(%i2) block ([prev], prev: integrate (x^5, x),
               ev (prev, x=2) - ev (prev, x=1));
                               21
(%o2)                          --
                               2

A compound statement may comprise other compound statements. Whether a statement be simple or compound, %% is the value of the previous statement.

(%i3) block (block (a^n, %%*42), %%/6);
                                 n
(%o3)                         7 a

Within a compound statement, the value of %% may be inspected at a break prompt, which is opened by executing the break function. For example, entering %%; in the following example yields 42.

(%i4) block (a: 42, break ())$

Entering a Maxima break point. Type 'exit;' to resume.
_%%;
42
_
Categories: Global variables ·
Function: %th (i)

The value of the i’th previous output expression. That is, if the next expression to be computed is the n’th output, %th (m) is the (n - m)’th output.

%th is recognized by batch and load. In a file processed by batch, %th has the same meaning as at the interactive prompt. In a file processed by load, %th refers to output expressions most recently computed at the interactive prompt or in a batch file; %th does not refer to output expressions in the file being processed.

See also % and %%.

Example:

%th is useful in batch files or for referring to a group of output expressions. This example sets s to the sum of the last five output expressions.

(%i1) 1;2;3;4;5;
(%o1)                           1
(%o2)                           2
(%o3)                           3
(%o4)                           4
(%o5)                           5
(%i6) block (s: 0, for i:1 thru 5 do s: s + %th(i), s);
(%o6)                          15
Categories: Console interaction ·
Special symbol: ?

As prefix to a function or variable name, ? signifies that the name is a Lisp name, not a Maxima name. For example, ?round signifies the Lisp function ROUND. See Lisp and Maxima for more on this point.

The notation ? word (a question mark followed a word, separated by whitespace) is equivalent to describe("word"). The question mark must occur at the beginning of an input line; otherwise it is not recognized as a request for documentation. See also describe.

Categories: Help · Console interaction ·
Special symbol: ??

The notation ?? word (?? followed a word, separated by whitespace) is equivalent to describe("word", inexact). The question mark must occur at the beginning of an input line; otherwise it is not recognized as a request for documentation. See also describe.

Categories: Help · Console interaction ·
Input terminator: $

The dollar sign $ terminates an input expression, and the most recent output % and an output label, e.g. %o1, are assigned the result, but the result is not displayed.

See also ;.

Example:

(%i1) 1 + 2 + 3 $
(%i2) %;
(%o2)                           6
(%i3) %o1;
(%o3)                           6
Input terminator: ;

The semicolon ; terminates an input expression, and the resulting output is displayed.

See also $.

Example:

(%i1) 1 + 2 + 3;
(%o1)                           6
Option variable: inchar

Default value: %i

inchar is the prefix of the labels of expressions entered by the user. Maxima automatically constructs a label for each input expression by concatenating inchar and linenum.

inchar may be assigned any string or symbol, not necessarily a single character. Because Maxima internally takes into account only the first char of the prefix, the prefixes inchar, outchar, and linechar should have a different first char. Otherwise some commands like kill(inlabels) do not work as expected.

See also labels.

Example:

(%i1) inchar: "input";
(%o1)                         input
(input2) expand((a+b)^3);
                     3        2      2      3
(%o2)               b  + 3 a b  + 3 a  b + a
System variable: infolists

Default value: []

infolists is a list of the names of all of the information lists in Maxima. These are:

labels

All bound %i, %o, and %t labels.

values

All bound atoms which are user variables, not Maxima options or switches, created by : or :: or functional binding.

functions

All user-defined functions, created by := or define.

arrays

All arrays, hashed arrays and memoizing functions.

macros

All user-defined macro functions, created by ::=.

myoptions

All options ever reset by the user (whether or not they are later reset to their default values).

rules

All user-defined pattern matching and simplification rules, created by tellsimp, tellsimpafter, defmatch, or defrule.

aliases

All atoms which have a user-defined alias, created by the alias, ordergreat, orderless functions or by declaring the atom as a noun with declare.

dependencies

All atoms which have functional dependencies, created by the depends, dependencies, or gradef functions.

gradefs

All functions which have user-defined derivatives, created by the gradef function.

props

All atoms which have any property other than those mentioned above, such as properties established by atvalue or matchdeclare, etc., as well as properties established in the declare function.

structures

All structs defined using defstruct.

let_rule_packages

All user-defined let rule packages plus the special package default_let_rule_package. (default_let_rule_package is the name of the rule package used when one is not explicitly set by the user.)

Function: kill
    kill (a_1, …, a_n)
    kill (labels)
    kill (inlabels, outlabels, linelabels)
    kill (n)
    kill ([m, n])
    kill (values, functions, arrays, …)
    kill (all)
    kill (allbut (a_1, …, a_n))

Removes all bindings (value, function, array, or rule) from the arguments a_1, …, a_n. An argument a_k may be a symbol or a single array element. When a_k is a single array element, kill unbinds that element without affecting any other elements of the array.

Several special arguments are recognized. Different kinds of arguments may be combined, e.g., kill (inlabels, functions, allbut (foo, bar)).

kill (labels) unbinds all input, output, and intermediate expression labels created so far. kill (inlabels) unbinds only input labels which begin with the current value of inchar. Likewise, kill (outlabels) unbinds only output labels which begin with the current value of outchar, and kill (linelabels) unbinds only intermediate expression labels which begin with the current value of linechar.

kill (n), where n is an integer, unbinds the n most recent input and output labels.

kill ([m, n]) unbinds input and output labels m through n.

kill (infolist), where infolist is any item in infolists (such as values, functions, or arrays) unbinds all items in infolist. See also infolists.

kill (all) unbinds all items on all infolists. kill (all) does not reset global variables to their default values; see reset on this point.

kill (allbut (a_1, ..., a_n)) unbinds all items on all infolists except for a_1, …, a_n. kill (allbut (infolist)) unbinds all items except for the ones on infolist, where infolist is values, functions, arrays, etc.

The memory taken up by a bound property is not released until all symbols are unbound from it. In particular, to release the memory taken up by the value of a symbol, one unbinds the output label which shows the bound value, as well as unbinding the symbol itself.

kill quotes its arguments. The quote-quote operator '' defeats quotation.

kill (symbol) unbinds all properties of symbol. In contrast, the functions remvalue, remfunction, remarray, and remrule unbind a specific property. Note that facts declared by assume don’t require a symbol they apply to, therefore aren’t stored as properties of symbols and therefore aren’t affected by kill.

kill always returns done, even if an argument has no binding.

Function: labels (symbol)

Returns the list of input, output, or intermediate expression labels which begin with symbol. Typically symbol is the value of inchar, outchar, or linechar. If no labels begin with symbol, labels returns an empty list.

By default, Maxima displays the result of each user input expression, giving the result an output label. The output display is suppressed by terminating the input with $ (dollar sign) instead of ; (semicolon). An output label is constructed and bound to the result, but not displayed, and the label may be referenced in the same way as displayed output labels. See also %, %%, and %th.

Intermediate expression labels can be generated by some functions. The option variable programmode controls whether solve and some other functions generate intermediate expression labels instead of returning a list of expressions. Some other functions, such as ldisplay, always generate intermediate expression labels.

See also inchar, outchar, linechar, and infolists.

System variable: labels

The variable labels is the list of input, output, and intermediate expression labels, including all previous labels if inchar, outchar, or linechar were redefined.

Option variable: linechar

Default value: %t

linechar is the prefix of the labels of intermediate expressions generated by Maxima. Maxima constructs a label for each intermediate expression (if displayed) by concatenating linechar and linenum.

linechar may be assigned any string or symbol, not necessarily a single character. Because Maxima internally takes into account only the first char of the prefix, the prefixes inchar, outchar, and linechar should have a different first char. Otherwise some commands like kill(inlabels) do not work as expected.

Intermediate expressions might or might not be displayed. See programmode and labels.

System variable: linenum

The line number of the current pair of input and output expressions.

System variable: myoptions

Default value: []

myoptions is the list of all options ever reset by the user, whether or not they get reset to their default value.

Option variable: nolabels

Default value: false

When nolabels is true, input and output result labels (%i and %o, respectively) are displayed, but the labels are not bound to results, and the labels are not appended to the labels list. Since labels are not bound to results, garbage collection can recover the memory taken up by the results.

Otherwise input and output result labels are bound to results, and the labels are appended to the labels list.

Intermediate expression labels (%t) are not affected by nolabels; whether nolabels is true or false, intermediate expression labels are bound and appended to the labels list.

See also batch, load, and labels.

Option variable: optionset

Default value: false

When optionset is true, Maxima prints out a message whenever a Maxima option is reset. This is useful if the user is doubtful of the spelling of some option and wants to make sure that the variable he assigned a value to was truly an option variable.

Example:

(%i1) optionset:true;
assignment: assigning to option optionset
(%o1)                         true
(%i2) gamma_expand:true;
assignment: assigning to option gamma_expand
(%o2)                         true
Option variable: outchar

Default value: %o

outchar is the prefix of the labels of expressions computed by Maxima. Maxima automatically constructs a label for each computed expression by concatenating outchar and linenum.

outchar may be assigned any string or symbol, not necessarily a single character. Because Maxima internally takes into account only the first char of the prefix, the prefixes inchar, outchar and linechar should have a different first char. Otherwise some commands like kill(inlabels) do not work as expected.

See also labels.

Example:

(%i1) outchar: "output";
(output1)                    output
(%i2) expand((a+b)^3);
                     3        2      2      3
(output2)           b  + 3 a b  + 3 a  b + a
Function: playback
    playback ()
    playback (n)
    playback ([m, n])
    playback ([m])
    playback (input)
    playback (slow)
    playback (time)
    playback (grind)

Displays input, output, and intermediate expressions, without recomputing them. playback only displays the expressions bound to labels; any other output (such as text printed by print or describe, or error messages) is not displayed. See also labels.

playback quotes its arguments. The quote-quote operator '' defeats quotation. playback always returns done.

playback () (with no arguments) displays all input, output, and intermediate expressions generated so far. An output expression is displayed even if it was suppressed by the $ terminator when it was originally computed.

playback (n) displays the most recent n expressions. Each input, output, and intermediate expression counts as one.

playback ([m, n]) displays input, output, and intermediate expressions with numbers from m through n, inclusive.

playback ([m]) is equivalent to playback ([m, m]); this usually prints one pair of input and output expressions.

playback (input) displays all input expressions generated so far.

playback (slow) pauses between expressions and waits for the user to press enter. This behavior is similar to demo. playback (slow) is useful in conjunction with save or stringout when creating a secondary-storage file in order to pick out useful expressions.

playback (time) displays the computation time for each expression.

playback (grind) displays input expressions in the same format as the grind function. Output expressions are not affected by the grind option. See grind.

Arguments may be combined, e.g., playback ([5, 10], grind, time, slow).

Option variable: prompt

Default value: _

prompt is the prompt symbol of the demo function, playback (slow) mode, and the Maxima break loop (as invoked by break).

Function: quit ()

Terminates the Maxima session. Note that the function must be invoked as quit(); or quit()$, not quit by itself.

To stop a lengthy computation, type control-C. The default action is to return to the Maxima prompt. If *debugger-hook* is nil, control-C opens the Lisp debugger. See also Debugging.

Categories: Console interaction ·
Function: read (expr_1, …, expr_n)

Prints expr_1, …, expr_n, then reads one expression from the console and returns the evaluated expression. The expression is terminated with a semicolon ; or dollar sign $.

See also readonly

Example:

(%i1) foo: 42$ 
(%i2) foo: read ("foo is", foo, " -- enter new value.")$
foo is 42  -- enter new value. 
(a+b)^3;
(%i3) foo;
                                     3
(%o3)                         (b + a)
Categories: Console interaction ·
Function: readonly (expr_1, …, expr_n)

Prints expr_1, …, expr_n, then reads one expression from the console and returns the expression (without evaluation). The expression is terminated with a ; (semicolon) or $ (dollar sign).

See also read.

Examples:

(%i1) aa: 7$
(%i2) foo: readonly ("Enter an expression:");
Enter an expression: 
2^aa;
                                  aa
(%o2)                            2
(%i3) foo: read ("Enter an expression:");
Enter an expression: 
2^aa;
(%o3)                            128
Categories: Console interaction ·
Function: reset ()

Resets many global variables and options, and some other variables, to their default values.

reset processes the variables on the Lisp list *variable-initial-values*. The Lisp macro defmvar puts variables on this list (among other actions). Many, but not all, global variables and options are defined by defmvar, and some variables defined by defmvar are not global variables or options.

Categories: Session management ·
Option variable: showtime

Default value: false

When showtime is true, the computation time and elapsed time is printed with each output expression.

The computation time is always recorded, so time and playback can display the computation time even when showtime is false.

See also timer.

Function: to_lisp ()

Enters the Lisp system under Maxima. (to-maxima) returns to Maxima.

Example:

Define a function and enter the Lisp system under Maxima. The definition is inspected on the property list, then the function definition is extracted, factored and stored in the variable $result. The variable can be used in Maxima after returning to Maxima.

(%i1) f(x):=x^2+x;
                                  2
(%o1)                    f(x) := x  + x
(%i2) to_lisp();
Type (to-maxima) to restart, ($quit) to quit Maxima.
MAXIMA> (symbol-plist '$f)
(MPROPS (NIL MEXPR ((LAMBDA) ((MLIST) $X) 
                             ((MPLUS) ((MEXPT) $X 2) $X))))
MAXIMA> (setq $result ($factor (caddr (mget '$f 'mexpr))))
((MTIMES SIMP FACTORED) $X ((MPLUS SIMP IRREDUCIBLE) 1 $X))
MAXIMA> (to-maxima)
Returning to Maxima
(%o2)                         true
(%i3) result;
(%o3)                       x (x + 1)
Categories: Console interaction ·
Function: eval_string_lisp (str)

Sequentially read lisp forms from the string str and evaluate them. Any values produced from the last form are returned as a Maxima list.

Examples:

(%i1) eval_string_lisp ("");
(%o1) []
(%i2) eval_string_lisp ("(values)");
(%o2) []
(%i3) eval_string_lisp ("69");
(%o3) [69]
(%i4) eval_string_lisp ("1 2 3");
(%o4) [3]
(%i5) eval_string_lisp ("(values 1 2 3)");
(%o5) [1,2,3]
(%i6) eval_string_lisp ("(defun $foo (x) (* 2 x))");
(%o6) [foo]
(%i7) foo (5);
(%o7) 10

See also eval_string.

Categories: Debugging · Evaluation ·
System variable: values

Initial value: []

values is a list of all bound user variables (not Maxima options or switches). The list comprises symbols bound by :, or ::.

If the value of a variable is removed with the commands kill, remove, or remvalue the variable is deleted from values.

See functions for a list of user defined functions.

Examples:

First, values shows the symbols a, b, and c, but not d, it is not bound to a value, and not the user function f. The values are removed from the variables. values is the empty list.

(%i1) [a:99, b:: a-90, c:a-b, d, f(x):=x^2];
                                           2
(%o1)              [99, 9, 90, d, f(x) := x ]
(%i2) values;
(%o2)                       [a, b, c]
(%i3) [kill(a), remove(b,value), remvalue(c)];
(%o3)                   [done, done, [c]]
(%i4) values;
(%o4)                          []
Categories: Evaluation · Global variables ·

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