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# 4. Command Line

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## 4.1 Introduction to Command Line

Operator: "'"

The single quote operator `'` prevents evaluation.

Applied to a symbol, the single quote prevents evaluation of the symbol.

Applied to a function call, the single quote prevents evaluation of the function call, although the arguments of the function are still evaluated (if evaluation is not otherwise prevented). The result is the noun form of the function call.

Applied to a parenthesized expression, the single quote prevents evaluation of all symbols and function calls in the expression. E.g., `'(f(x))` means do not evaluate the expression `f(x)`. `'f(x)` (with the single quote applied to `f` instead of `f(x)`) means return the noun form of `f` applied to `[x]`.

The single quote does not prevent simplification.

When the global flag `noundisp` is `true`, nouns display with a single quote. This switch is always `true` when displaying function definitions.

See also the quote-quote operator `''` and `nouns`.

Examples:

Applied to a symbol, the single quote prevents evaluation of the symbol.

 ```(%i1) aa: 1024; (%o1) 1024 (%i2) aa^2; (%o2) 1048576 (%i3) 'aa^2; 2 (%o3) aa (%i4) ''%; (%o4) 1048576 ```

Applied to a function call, the single quote prevents evaluation of the function call. The result is the noun form of the function call.

 ```(%i1) x0: 5; (%o1) 5 (%i2) x1: 7; (%o2) 7 (%i3) integrate (x^2, x, x0, x1); 218 (%o3) --- 3 (%i4) 'integrate (x^2, x, x0, x1); 7 / [ 2 (%o4) I x dx ] / 5 (%i5) %, nouns; 218 (%o5) --- 3 ```

Applied to a parenthesized expression, the single quote prevents evaluation of all symbols and function calls in the expression.

 ```(%i1) aa: 1024; (%o1) 1024 (%i2) bb: 19; (%o2) 19 (%i3) sqrt(aa) + bb; (%o3) 51 (%i4) '(sqrt(aa) + bb); (%o4) bb + sqrt(aa) (%i5) ''%; (%o5) 51 ```

The single quote does not prevent simplification.

 ```(%i1) sin (17 * %pi) + cos (17 * %pi); (%o1) - 1 (%i2) '(sin (17 * %pi) + cos (17 * %pi)); (%o2) - 1 ```
Operator: "''"

The `''` (double single quotes) operator causes an extra evaluation to occur. E.g., `''%i4` will re-evaluate input line `%i4`. `''(f(x))` means evaluate the expression `f(x)` an extra time. `''f(x)` (with the double single quotes applied to `f` instead of `f(x)`) means return the verb form of `f` applied to `[x]`.

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## 4.2 Definitions for Command Line

Function: alias (new_name_1, old_name_1, ..., new_name_n, old_name_n)

provides an alternate name for a (user or system) function, variable, array, etc. Any even number of arguments may be used.

Option variable: debugmode

Default value: `false`

When a Maxima error occurs, Maxima will start the debugger if `debugmode` is `true`. The user may enter commands to examine the call stack, set breakpoints, step through Maxima code, and so on. See `debugging` for a list of debugger commands.

Enabling `debugmode` will not catch Lisp errors.

Function: ev (expr, arg_1, ..., arg_n)

Evaluates the expression expr in the environment specified by the arguments arg_1, ..., arg_n. The arguments are switches (Boolean flags), assignments, equations, and functions. `ev` returns the result (another expression) of the evaluation.

The evaluation is carried out in steps, as follows.

1. First the environment is set up by scanning the arguments which may be any or all of the following.
• `simp` causes expr to be simplified regardless of the setting of the switch `simp` which inhibits simplification if `false`.
• `noeval` supresses the evaluation phase of `ev` (see step (4) below). This is useful in conjunction with the other switches and in causing expr to be resimplified without being reevaluated.
• `nouns` causes the evaluation of noun forms (typically unevaluated functions such as `'integrate` or `'diff`) in expr.
• `expand` causes expansion.
• `expand (m, n)` causes expansion, setting the values of `maxposex` and `maxnegex` to m and n respectively.
• `detout` causes any matrix inverses computed in expr to have their determinant kept outside of the inverse rather than dividing through each element.
• `diff` causes all differentiations indicated in expr to be performed.
• `derivlist (x, y, z, ...)` causes only differentiations with respect to the indicated variables.
• `float` causes non-integral rational numbers to be converted to floating point.
• `numer` causes some mathematical functions (including exponentiation) with numerical arguments to be evaluated in floating point. It causes variables in expr which have been given numervals to be replaced by their values. It also sets the `float` switch on.
• `pred` causes predicates (expressions which evaluate to `true` or `false`) to be evaluated.
• `eval` causes an extra post-evaluation of expr to occur. (See step (5) below.)
• `A` where `A` is an atom declared to be an evaluation flag (see `evflag`) causes `A` to be bound to `true` during the evaluation of expr.
• `V: expression` (or alternately `V=expression`) causes `V` to be bound to the value of `expression` during the evaluation of expr. Note that if `V` is a Maxima option, then `expression` is used for its value during the evaluation of expr. If more than one argument to `ev` is of this type then the binding is done in parallel. If `V` is a non-atomic expression then a substitution rather than a binding is performed.
• `F` where `F`, a function name, has been declared to be an evaluation function (see `evfun`) causes `F` to be applied to expr.
• Any other function names (e.g., `sum`) cause evaluation of occurrences of those names in expr as though they were verbs.
• In addition a function occurring in expr (say `F(x)`) may be defined locally for the purpose of this evaluation of expr by giving `F(x) := expression` as an argument to `ev`.
• If an atom not mentioned above or a subscripted variable or subscripted expression was given as an argument, it is evaluated and if the result is an equation or assignment then the indicated binding or substitution is performed. If the result is a list then the members of the list are treated as if they were additional arguments given to `ev`. This permits a list of equations to be given (e.g. `[X=1, Y=A**2]`) or a list of names of equations (e.g., `[%t1, %t2]` where `%t1` and `%t2` are equations) such as that returned by `solve`.

The arguments of `ev` may be given in any order with the exception of substitution equations which are handled in sequence, left to right, and evaluation functions which are composed, e.g., `ev (expr, ratsimp, realpart)` is handled as `realpart (ratsimp (expr))`.

The `simp`, `numer`, `float`, and `pred` switches may also be set locally in a block, or globally in Maxima so that they will remain in effect until being reset.

If expr is a canonical rational expression (CRE), then the expression returned by `ev` is also a CRE, provided the `numer` and `float` switches are not both `true`.

2. During step (1), a list is made of the non-subscripted variables appearing on the left side of equations in the arguments or in the value of some arguments if the value is an equation. The variables (subscripted variables which do not have associated array functions as well as non-subscripted variables) in the expression expr are replaced by their global values, except for those appearing in this list. Usually, expr is just a label or `%` (as in `%i2` in the example below), so this step simply retrieves the expression named by the label, so that `ev` may work on it.
3. If any substitutions are indicated by the arguments, they are carried out now.
4. The resulting expression is then re-evaluated (unless one of the arguments was `noeval`) and simplified according to the arguments. Note that any function calls in expr will be carried out after the variables in it are evaluated and that `ev(F(x))` thus may behave like `F(ev(x))`.
5. If one of the arguments was `eval`, steps (3) and (4) are repeated.

Examples

 ```(%i1) sin(x) + cos(y) + (w+1)^2 + 'diff (sin(w), w); d 2 (%o1) cos(y) + sin(x) + -- (sin(w)) + (w + 1) dw (%i2) ev (%, sin, expand, diff, x=2, y=1); 2 (%o2) cos(w) + w + 2 w + cos(1) + 1.909297426825682 ```

An alternate top level syntax has been provided for `ev`, whereby one may just type in its arguments, without the `ev()`. That is, one may write simply

 ```expr, arg_1, ..., arg_n ```

This is not permitted as part of another expression, e.g., in functions, blocks, etc.

Notice the parallel binding process in the following example.

 ```(%i3) programmode: false; (%o3) false (%i4) x+y, x: a+y, y: 2; (%o4) y + a + 2 (%i5) 2*x - 3*y = 3\$ (%i6) -3*x + 2*y = -4\$ (%i7) solve ([%o5, %o6]); Solution 1 (%t7) y = - - 5 6 (%t8) x = - 5 (%o8) [[%t7, %t8]] (%i8) %o6, %o8; (%o8) - 4 = - 4 (%i9) x + 1/x > gamma (1/2); 1 (%o9) x + - > sqrt(%pi) x (%i10) %, numer, x=1/2; (%o10) 2.5 > 1.772453850905516 (%i11) %, pred; (%o11) true ```
Property: evflag

Some Boolean flags have the `evflag` property. `ev` treats such flags specially. A flag with the `evflag` property will be bound to `true` during the execution of `ev` if it is mentioned in the call to `ev`. For example, `demoivre` and `ratfac` are bound to `true` during the call `ev (%, demoivre, ratfac)`.

The flags which have the `evflag` property are: `algebraic`, `cauchysum`, `demoivre`, `dotscrules`, `%emode`, `%enumer`, `exponentialize`, `exptisolate`, `factorflag`, `float`, `halfangles`, `infeval`, `isolate_wrt_times`, `keepfloat`, `letrat`, `listarith`, `logabs`, `logarc`, `logexpand`, `lognegint`, `lognumer`, `m1pbranch`, `numer_pbranch`, `programmode`, `radexpand`, `ratalgdenom`, `ratfac`, `ratmx`, `ratsimpexpons`, `simp`, `simpsum`, `sumexpand`, and `trigexpand`.

The construct `:lisp (putprop '|\$foo| t 'evflag)` gives the `evflag` property to the variable `foo`, so `foo` is bound to `true` during the call `ev (%, foo)`. Equivalently, `ev (%, foo:true)` has the same effect.

Property: evfun

Some functions have the `evfun` property. `ev` treats such functions specially. A function with the `evfun` property will be applied during the execution of `ev` if it is mentioned in the call to `ev`. For example, `ratsimp` and `radcan` will be applied during the call `ev (%, ratsimp, radcan)`.

The functions which have the `evfun` property are: `bfloat`, `factor`, `fullratsimp`, `logcontract`, `polarform`, `radcan`, `ratexpand`, `ratsimp`, `rectform`, `rootscontract`, `trigexpand`, and `trigreduce`.

The construct `:lisp (putprop '|\$foo| t 'evfun)` gives the `evfun` property to the function `foo`, so that `foo` is applied during the call `ev (%, foo)`. Equivalently, `foo (ev (%))` has the same effect.

Option variable: infeval

Enables "infinite evaluation" mode. `ev` repeatedly evaluates an expression until it stops changing. To prevent a variable, say `X`, from being evaluated away in this mode, simply include `X='X` as an argument to `ev`. Of course expressions such as `ev (X, X=X+1, infeval)` will generate an infinite loop.

Function: kill (symbol_1, ..., symbol_n)
Function: kill (labels)
Function: kill (inlabels, outlabels, linelabels)
Function: kill (n)
Function: kill ([m, n])
Function: kill (values, functions, arrays, ...)
Function: kill (all)
Function: kill (allbut (symbol_1, ..., symbol_n))

Removes all bindings (value, function, array, or rule) from the arguments symbol_1, ..., symbol_n. An argument may be a single array element or subscripted function.

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 (symbol_1, ..., symbol_n))` unbinds all items on all infolists except for symbol_1, ..., symbol_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 double single quotes operator, `''`, defeats the quotation.

`kill (symbol)` unbinds all properties of symbol. In contrast, `remvalue`, `remfunction`, `remarray`, and `remrule` unbind a specific property.

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

Function: labels (symbol)
System variable: labels

Returns the list of input, output, or intermediate expression labels which begin with symbol. Typically symbol is the value of `inchar`, `outchar`, or `linechar`. The label character may be given with or without a percent sign, so, for example, `i` and `%i` yield the same result.

If no labels begin with symbol, `labels` returns an empty list.

The function `labels` quotes its argument. The double single quotes operator `''` defeats quotation. For example, `labels (''inchar)` returns the input labels which begin with the current input label character.

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

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 flag `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: 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.

Function: playback ()
Function: playback (n)
Function: playback ([m, n])
Function: playback ([m])
Function: playback (input)
Function: playback (slow)
Function: playback (time)
Function: 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 double single quotes 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)`.

Function: printprops (a, i)
Function: printprops ([a_1, ..., a_n], i)
Function: printprops (all, i)

Displays the property with the indicator i associated with the atom a. a may also be a list of atoms or the atom `all` in which case all of the atoms with the given property will be used. For example, `printprops ([f, g], atvalue)`. `printprops` is for properties that cannot otherwise be displayed, i.e. for `atvalue`, `atomgrad`, `gradef`, and `matchdeclare`.

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`.

Function: remfunction (f_1, ..., f_n)
Function: remfunction (all)

Unbinds the function definitions of the symbols f_1, ..., f_n. The arguments may be the names of ordinary functions (created by `:=` or `define`) or macro functions (created by `::=`).

`remfunction (all)` unbinds all function definitions.

`remfunction` quotes its arguments.

`remfunction` returns a list of the symbols for which the function definition was unbound. `false` is returned in place of any symbol for which there is no function definition.

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.

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: sstatus (feature, package)

Sets the status of feature in package. After `sstatus (feature, package)` is executed, `status (feature, package)` returns `true`. This can be useful for package writers, to keep track of what features they have loaded in.

Function: to_lisp ()

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

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 `:=`.

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