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# 3. Help

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## 3.1 Documentation

The Maxima on-line user's manual can be viewed in different forms. From the Maxima interactive prompt, the user's manual is viewed as plain text by the `?` command (i.e., the `describe` function). The user's manual is viewed as `info` hypertext by the `info` viewer program and as a web page by any ordinary web browser.

`example` displays examples for many Maxima functions. For example,

    (%i1) example (integrate);

yields

    (%i2) test(f):=block([u],u:integrate(f,x),ratsimp(f-diff(u,x)))
    (%o2) test(f) := block([u], u : integrate(f, x),
                                             ratsimp(f - diff(u, x)))
    (%i3) test(sin(x))
    (%o3)                           0
    (%i4) test(1/(x+1))
    (%o4)                           0
    (%i5) test(1/(x^2+1))
    (%o5)                           0

and additional output.

Categories: Console interaction

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## 3.2 Functions and Variables for Help

Function: apropos (string)

  Searches for Maxima names which have string appearing anywhere within them. Thus, `apropos (exp)` returns a list of all the flags and functions which have `exp` as part of their names, such as `expand`, `exp`, and `exponentialize`. Thus if you can only remember part of the name of something you can use this command to find the rest of the name. Similarly, you could say `apropos (tr_)` to find a list of many of the switches relating to the translator, most of which begin with `tr_`.

  `apropos("")` returns a list with all Maxima names.

  `apropos` returns the empty list `[]`, if no name is found.

  Example:

  Show all Maxima symbols which have `"gamma"` in the name:

      (%i1) apropos("gamma");
      (%o1) [%gamma, gamma, gammalim, gamma_expand, gamma_greek,
      gamma_incomplete, gamma_incomplete_generalized,
      gamma_incomplete_regularized, Gamma, log_gamma, makegamma,
      prefer_gamma_incomplete,
      gamma_incomplete_generalized_regularized]

  Categories: Help

Function: demo (filename)

  Evaluates Maxima expressions in filename and displays the results. `demo` pauses after evaluating each expression and continues after the user enters a carriage return. (If running in Xmaxima, `demo` may need to see a semicolon `;` followed by a carriage return.)

  `demo` searches the list of directories `file_search_demo` to find `filename`. If the file has the suffix `dem`, the suffix may be omitted. See also `file_search`.

  `demo` evaluates its argument. `demo` returns the name of the demonstration file.

  Example:

      (%i1) demo ("disol");

      batching /home/wfs/maxima/share/simplification/disol.dem
       At the _ prompt, type ';' followed by enter to get next demo
      (%i2)                      load(disol)

      _
      (%i3)           exp1 : a (e (g + f) + b (d + c))
      (%o3)               a (e (g + f) + b (d + c))

      _
      (%i4)                disolate(exp1, a, b, e)
      (%t4)                         d + c

      (%t5)                         g + f

      (%o5)                   a (%t5 e + %t4 b)

      _

  Categories: Help · Console interaction · File input

Function: describe (string)
Function: describe (string, exact)
Function: describe (string, inexact)

  `describe(string)` is equivalent to `describe(string, exact)`.

  `describe(string, exact)` finds an item with title equal (case-insensitive) to string, if there is any such item.

  `describe(string, inexact)` finds all documented items which contain string in their titles. If there is more than one such item, Maxima asks the user to select an item or items to display.

  At the interactive prompt, `? foo` (with a space between `?` and `foo`) is equivalent to `describe("foo", exact)`, and `?? foo` is equivalent to `describe("foo", inexact)`.

  `describe("", inexact)` yields a list of all topics documented in the on-line manual.

  `describe` quotes its argument. `describe` returns `true` if some documentation is found, otherwise `false`.

  See also Documentation.

  Example:

      (%i1) ?? integ
       0: Functions and Variables for Elliptic Integrals
       1: Functions and Variables for Integration
       2: Introduction to Elliptic Functions and Integrals
       3: Introduction to Integration
       4: askinteger  (Functions and Variables for Simplification)
       5: integerp  (Functions and Variables for Miscellaneous Options)
       6: integer_partitions  (Functions and Variables for Sets)
       7: integrate  (Functions and Variables for Integration)
       8: integrate_use_rootsof  (Functions and Variables for
          Integration)
       9: integration_constant_counter  (Functions and Variables for
          Integration)
       10: nonnegintegerp  (Functions and Variables for linearalgebra)
      Enter space-separated numbers, `all' or `none': 7 8

       -- Function: integrate (<expr>, <x>)
       -- Function: integrate (<expr>, <x>, <a>, <b>)
           Attempts to symbolically compute the integral of <expr> with
           respect to <x>.  `integrate (<expr>, <x>)' is an indefinite
           integral, while `integrate (<expr>, <x>, <a>, <b>)' is a
           definite integral, [...]

       -- Option variable: integrate_use_rootsof
           Default value: `false'

           When `integrate_use_rootsof' is `true' and the denominator of
           a rational function cannot be factored, `integrate' returns
           the integral in a form which is a sum over the roots (not yet
           known) of the denominator.
           [...]

  In this example, items 7 and 8 were selected (output is shortened as indicated by `[...]`. All or none of the items could have been selected by entering `all` or `none`, which can be abbreviated `a` or `n`, respectively.

  Categories: Help · Console interaction

Function: example (topic)
Function: example ()

  `example (topic)` displays some examples of topic, which is a symbol or a string. To get examples for operators like `if`, `do`, or `lambda` the argument must be a string, e.g. `example ("do")`. `example` is not case sensitive. Most topics are function names.

  `example ()` returns the list of all recognized topics.

  The name of the file containing the examples is given by the global option variable `manual_demo`, which defaults to `"manual.demo"`.

  `example` quotes its argument. `example` returns `done` unless no examples are found or there is no argument, in which case `example` returns the list of all recognized topics.

  Examples:

      (%i1) example(append);
      (%i2) append([x+y,0,-3.2],[2.5e+20,x])
      (%o2)             [y + x, 0, - 3.2, 2.5e+20, x]
      (%o2)                         done
      (%i3) example("lambda");

      (%i4) lambda([x,y,z],z^2+y^2+x^2)
                                          2    2    2
      (%o4)            lambda([x, y, z], z  + y  + x )
      (%i5) %(1,2,a)
                                    2
      (%o5)                        a  + 5
      (%i6) a+2+1
      (%o6)                         a + 3
      (%o6)                         done

  Categories: Help · Console interaction

Option variable: manual_demo

  Default value: `"manual.demo"`

  `manual_demo` specifies the name of the file containing the examples for the function `example`. See `example`.

  Categories: Help · Global variables

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