<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ -->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Getting Help (GNU Octave (version 5.1.0))</title>
<meta name="description" content="Getting Help (GNU Octave (version 5.1.0))">
<meta name="keywords" content="Getting Help (GNU Octave (version 5.1.0))">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<link href="index.html#Top" rel="start" title="Top">
<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Getting-Started.html#Getting-Started" rel="up" title="Getting Started">
<link href="Command-Line-Editing.html#Command-Line-Editing" rel="next" title="Command Line Editing">
<link href="Quitting-Octave.html#Quitting-Octave" rel="prev" title="Quitting Octave">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.indentedblock {margin-right: 0em}
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smalllisp {margin-left: 3.2em}
kbd {font-style: oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nolinebreak {white-space: nowrap}
span.roman {font-family: initial; font-weight: normal}
span.sansserif {font-family: sans-serif; font-weight: normal}
ul.no-bullet {list-style: none}
-->
</style>
<link rel="stylesheet" type="text/css" href="octave.css">
</head>
<body lang="en">
<a name="Getting-Help"></a>
<div class="header">
<p>
Next: <a href="Command-Line-Editing.html#Command-Line-Editing" accesskey="n" rel="next">Command Line Editing</a>, Previous: <a href="Quitting-Octave.html#Quitting-Octave" accesskey="p" rel="prev">Quitting Octave</a>, Up: <a href="Getting-Started.html#Getting-Started" accesskey="u" rel="up">Getting Started</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Commands-for-Getting-Help"></a>
<h3 class="section">2.3 Commands for Getting Help</h3>
<a name="index-online-help"></a>
<a name="index-help_002c-online"></a>
<p>The entire text of this manual is available from the Octave prompt
via the command <kbd>doc</kbd>. In addition, the documentation for
individual user-written functions and variables is also available via
the <kbd>help</kbd> command. This section describes the commands used for
reading the manual and the documentation strings for user-supplied
functions and variables. See <a href="Function-Files.html#Function-Files">Function Files</a>, for more information
about how to document the functions you write.
</p>
<a name="XREFhelp"></a><dl>
<dt><a name="index-help"></a><em></em> <strong>help</strong> <em><var>name</var></em></dt>
<dt><a name="index-help-1"></a><em></em> <strong>help</strong> <em>--list</em></dt>
<dt><a name="index-help-2"></a><em></em> <strong>help</strong> <em>.</em></dt>
<dt><a name="index-help-3"></a><em></em> <strong>help</strong></dt>
<dd><p>Display the help text for <var>name</var>.
</p>
<p>For example, the command <kbd>help help</kbd> prints a short message describing
the <code>help</code> command.
</p>
<p>Given the single argument <code>--list</code>, list all operators, keywords,
built-in functions, and loadable functions available in the current session
of Octave.
</p>
<p>Given the single argument <code>.</code>, list all operators available in the
current session of Octave.
</p>
<p>If invoked without any arguments, <code>help</code> displays instructions on how
to access help from the command line.
</p>
<p>The help command can provide information about most operators, but
<var>name</var> must be enclosed by single or double quotes to prevent
the Octave interpreter from acting on <var>name</var>. For example,
<code>help "+"</code> displays help on the addition operator.
</p>
<p><strong>See also:</strong> <a href="#XREFdoc">doc</a>, <a href="#XREFlookfor">lookfor</a>, <a href="Status-of-Variables.html#XREFwhich">which</a>, <a href="#XREFinfo">info</a>.
</p></dd></dl>
<a name="XREFdoc"></a><dl>
<dt><a name="index-doc"></a><em></em> <strong>doc</strong> <em><var>function_name</var></em></dt>
<dt><a name="index-doc-1"></a><em></em> <strong>doc</strong></dt>
<dd><p>Display documentation for the function <var>function_name</var> directly from an
online version of the printed manual, using the GNU Info browser.
</p>
<p>If invoked without an argument, the manual is shown from the beginning.
</p>
<p>For example, the command <kbd>doc rand</kbd> starts the GNU Info browser at the
<code>rand</code> node in the online version of the manual.
</p>
<p>Once the GNU Info browser is running, help for using it is available using
the command <kbd>C-h</kbd>.
</p>
<p><strong>See also:</strong> <a href="#XREFhelp">help</a>.
</p></dd></dl>
<a name="XREFlookfor"></a><dl>
<dt><a name="index-lookfor"></a><em></em> <strong>lookfor</strong> <em><var>str</var></em></dt>
<dt><a name="index-lookfor-1"></a><em></em> <strong>lookfor</strong> <em>-all <var>str</var></em></dt>
<dt><a name="index-lookfor-2"></a><em>[<var>fcn</var>, <var>help1str</var>] =</em> <strong>lookfor</strong> <em>(<var>str</var>)</em></dt>
<dt><a name="index-lookfor-3"></a><em>[<var>fcn</var>, <var>help1str</var>] =</em> <strong>lookfor</strong> <em>("-all", <var>str</var>)</em></dt>
<dd><p>Search for the string <var>str</var> in the documentation of all functions in the
current function search path.
</p>
<p>By default, <code>lookfor</code> looks for <var>str</var> in just the first sentence of
the help string for each function found. The entire help text of each
function can be searched by using the <code>"-all"</code> argument. All searches
are case insensitive.
</p>
<p>When called with no output arguments, <code>lookfor</code> prints the list of
matching functions to the terminal. Otherwise, the output argument
<var>fcns</var> contains the function names and <var>help1str</var> contains the first
sentence from the help string of each function.
</p>
<p>Programming Note: The ability of <code>lookfor</code> to correctly identify the
first sentence of the help text is dependent on the format of the function’s
help. All Octave core functions are correctly formatted, but the same can
not be guaranteed for external packages and user-supplied functions.
Therefore, the use of the <code>"-all"</code> argument may be necessary to find
related functions that are not a part of Octave.
</p>
<p>The speed of lookup is greatly enhanced by having a cached documentation
file. See <code>doc_cache_create</code> for more information.
</p>
<p><strong>See also:</strong> <a href="#XREFhelp">help</a>, <a href="#XREFdoc">doc</a>, <a href="Status-of-Variables.html#XREFwhich">which</a>, <a href="Manipulating-the-Load-Path.html#XREFpath">path</a>, <a href="#XREFdoc_005fcache_005fcreate">doc_cache_create</a>.
</p></dd></dl>
<p>To see what is new in the current release of Octave, use the <code>news</code>
function.
</p>
<a name="XREFnews"></a><dl>
<dt><a name="index-news"></a><em></em> <strong>news</strong></dt>
<dt><a name="index-news-1"></a><em></em> <strong>news</strong> <em><var>package</var></em></dt>
<dd><p>Display the current NEWS file for Octave or an installed package.
</p>
<p>When called without an argument, display the NEWS file for Octave.
</p>
<p>When given a package name <var>package</var>, display the current NEWS file for
that package.
</p>
<p><strong>See also:</strong> <a href="System-Information.html#XREFver">ver</a>, <a href="Installing-and-Removing-Packages.html#XREFpkg">pkg</a>.
</p></dd></dl>
<a name="XREFinfo"></a><dl>
<dt><a name="index-info"></a><em></em> <strong>info</strong> <em>()</em></dt>
<dd><p>Display contact information for the GNU Octave community.
</p></dd></dl>
<a name="XREFwarranty"></a><dl>
<dt><a name="index-warranty-1"></a><em></em> <strong>warranty</strong> <em>()</em></dt>
<dd><p>Describe the conditions for copying and distributing Octave.
</p></dd></dl>
<p>The following functions can be used to change which programs are used
for displaying the documentation, and where the documentation can be
found.
</p>
<a name="XREFinfo_005ffile"></a><dl>
<dt><a name="index-info_005ffile"></a><em><var>val</var> =</em> <strong>info_file</strong> <em>()</em></dt>
<dt><a name="index-info_005ffile-1"></a><em><var>old_val</var> =</em> <strong>info_file</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-info_005ffile-2"></a><em></em> <strong>info_file</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the name of the
Octave info file.
</p>
<p>The default value is
<samp><var>octave-home</var>/info/octave.info</samp>, in
which <var>octave-home</var> is the root directory of the Octave installation.
The default value may be overridden by the environment variable
<code><span class="nolinebreak">OCTAVE_INFO_FILE</span></code><!-- /@w -->, or the command line argument
<samp>--info-file FNAME</samp>.
</p>
<p>When called from inside a function with the <code>"local"</code> option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
</p>
<p><strong>See also:</strong> <a href="#XREFinfo_005fprogram">info_program</a>, <a href="#XREFdoc">doc</a>, <a href="#XREFhelp">help</a>, <a href="#XREFmakeinfo_005fprogram">makeinfo_program</a>.
</p></dd></dl>
<a name="XREFinfo_005fprogram"></a><dl>
<dt><a name="index-info_005fprogram"></a><em><var>val</var> =</em> <strong>info_program</strong> <em>()</em></dt>
<dt><a name="index-info_005fprogram-1"></a><em><var>old_val</var> =</em> <strong>info_program</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-info_005fprogram-2"></a><em></em> <strong>info_program</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the name of the
info program to run.
</p>
<p>The default value is
<samp><var>octave-home</var>/libexec/octave/<var>version</var>/exec/<var>arch</var>/info</samp>
in which <var>octave-home</var> is the root directory of the Octave installation,
<var>version</var> is the Octave version number, and <var>arch</var> is the system
type (for example, <code>i686-pc-linux-gnu</code>). The default value may be
overridden by the environment variable
<code><span class="nolinebreak">OCTAVE_INFO_PROGRAM</span></code><!-- /@w -->, or the command line argument
<samp>--info-program NAME</samp>.
</p>
<p>When called from inside a function with the <code>"local"</code> option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
</p>
<p><strong>See also:</strong> <a href="#XREFinfo_005ffile">info_file</a>, <a href="#XREFdoc">doc</a>, <a href="#XREFhelp">help</a>, <a href="#XREFmakeinfo_005fprogram">makeinfo_program</a>.
</p></dd></dl>
<a name="XREFmakeinfo_005fprogram"></a><dl>
<dt><a name="index-makeinfo_005fprogram"></a><em><var>val</var> =</em> <strong>makeinfo_program</strong> <em>()</em></dt>
<dt><a name="index-makeinfo_005fprogram-1"></a><em><var>old_val</var> =</em> <strong>makeinfo_program</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-makeinfo_005fprogram-2"></a><em></em> <strong>makeinfo_program</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the name of the
program that Octave runs to format help text containing
Texinfo markup commands.
</p>
<p>The default value is <code>makeinfo</code>.
</p>
<p>When called from inside a function with the <code>"local"</code> option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
</p>
<p><strong>See also:</strong> <a href="#XREFtexi_005fmacros_005ffile">texi_macros_file</a>, <a href="#XREFinfo_005ffile">info_file</a>, <a href="#XREFinfo_005fprogram">info_program</a>, <a href="#XREFdoc">doc</a>, <a href="#XREFhelp">help</a>.
</p></dd></dl>
<a name="XREFtexi_005fmacros_005ffile"></a><dl>
<dt><a name="index-texi_005fmacros_005ffile"></a><em><var>val</var> =</em> <strong>texi_macros_file</strong> <em>()</em></dt>
<dt><a name="index-texi_005fmacros_005ffile-1"></a><em><var>old_val</var> =</em> <strong>texi_macros_file</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-texi_005fmacros_005ffile-2"></a><em></em> <strong>texi_macros_file</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the name of the
file containing Texinfo macros that are prepended to documentation strings
before they are passed to makeinfo.
</p>
<p>The default value is
<samp><var>octave-home</var>/share/octave/<var>version</var>/etc/macros.texi</samp>,
in which <var>octave-home</var> is the root directory of the Octave installation,
and <var>version</var> is the Octave version number.
The default value may be overridden by the environment variable
<code><span class="nolinebreak">OCTAVE_TEXI_MACROS_FILE</span></code><!-- /@w -->, or the command line argument
<samp>--texi-macros-file FNAME</samp>.
</p>
<p>When called from inside a function with the <code>"local"</code> option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
</p>
<p><strong>See also:</strong> <a href="#XREFmakeinfo_005fprogram">makeinfo_program</a>.
</p></dd></dl>
<a name="XREFdoc_005fcache_005ffile"></a><dl>
<dt><a name="index-doc_005fcache_005ffile"></a><em><var>val</var> =</em> <strong>doc_cache_file</strong> <em>()</em></dt>
<dt><a name="index-doc_005fcache_005ffile-1"></a><em><var>old_val</var> =</em> <strong>doc_cache_file</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-doc_005fcache_005ffile-2"></a><em></em> <strong>doc_cache_file</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the name of the
Octave documentation cache file.
</p>
<p>A cache file significantly improves the performance of the <code>lookfor</code>
command. The default value is
<samp><var>octave-home</var>/share/octave/<var>version</var>/etc/doc-cache</samp>,
in which <var>octave-home</var> is the root directory of the Octave installation,
and <var>version</var> is the Octave version number.
The default value may be overridden by the environment variable
<code><span class="nolinebreak">OCTAVE_DOC_CACHE_FILE</span></code><!-- /@w -->, or the command line argument
<samp>--doc-cache-file FNAME</samp>.
</p>
<p>When called from inside a function with the <code>"local"</code> option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
</p>
<p><strong>See also:</strong> <a href="#XREFdoc_005fcache_005fcreate">doc_cache_create</a>, <a href="#XREFlookfor">lookfor</a>, <a href="#XREFinfo_005fprogram">info_program</a>, <a href="#XREFdoc">doc</a>, <a href="#XREFhelp">help</a>, <a href="#XREFmakeinfo_005fprogram">makeinfo_program</a>.
</p>
<p><strong>See also:</strong> <a href="#XREFlookfor">lookfor</a>.
</p></dd></dl>
<a name="XREFbuilt_005fin_005fdocstrings_005ffile"></a><dl>
<dt><a name="index-built_005fin_005fdocstrings_005ffile"></a><em><var>val</var> =</em> <strong>built_in_docstrings_file</strong> <em>()</em></dt>
<dt><a name="index-built_005fin_005fdocstrings_005ffile-1"></a><em><var>old_val</var> =</em> <strong>built_in_docstrings_file</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-built_005fin_005fdocstrings_005ffile-2"></a><em></em> <strong>built_in_docstrings_file</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the name of the
file containing docstrings for built-in Octave functions.
</p>
<p>The default value is
<samp><var>octave-home</var>/share/octave/<var>version</var>/etc/built-in-docstrings</samp>,
in which <var>octave-home</var> is the root directory of the Octave installation,
and <var>version</var> is the Octave version number. The default value may be
overridden by the environment variable
<code><span class="nolinebreak">OCTAVE_BUILT_IN_DOCSTRINGS_FILE</span></code><!-- /@w -->, or the command line argument
<samp>--built-in-docstrings-file FNAME</samp>.
</p>
<p>Note: This variable is only used when Octave is initializing itself.
Modifying it during a running session of Octave will have no effect.
</p></dd></dl>
<a name="XREFsuppress_005fverbose_005fhelp_005fmessage"></a><dl>
<dt><a name="index-suppress_005fverbose_005fhelp_005fmessage"></a><em><var>val</var> =</em> <strong>suppress_verbose_help_message</strong> <em>()</em></dt>
<dt><a name="index-suppress_005fverbose_005fhelp_005fmessage-1"></a><em><var>old_val</var> =</em> <strong>suppress_verbose_help_message</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-suppress_005fverbose_005fhelp_005fmessage-2"></a><em></em> <strong>suppress_verbose_help_message</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that controls whether Octave
will add additional help information to the end of the output from
the <code>help</code> command and usage messages for built-in commands.
</p>
<p>When called from inside a function with the <code>"local"</code> option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
</p></dd></dl>
<p>The following functions are principally used internally by Octave for
generating the documentation. They are documented here for completeness
and because they may occasionally be useful for users.
</p>
<a name="XREFdoc_005fcache_005fcreate"></a><dl>
<dt><a name="index-doc_005fcache_005fcreate"></a><em></em> <strong>doc_cache_create</strong> <em>(<var>out_file</var>, <var>directory</var>)</em></dt>
<dt><a name="index-doc_005fcache_005fcreate-1"></a><em></em> <strong>doc_cache_create</strong> <em>(<var>out_file</var>)</em></dt>
<dt><a name="index-doc_005fcache_005fcreate-2"></a><em></em> <strong>doc_cache_create</strong> <em>()</em></dt>
<dd><p>Generate documentation cache for all functions in <var>directory</var>.
</p>
<p>A documentation cache is generated for all functions in <var>directory</var>
which may be a single string or a cell array of strings. The cache is used
to speed up the function <code>lookfor</code>.
</p>
<p>The cache is saved in the file <var>out_file</var> which defaults to the value
<samp>doc-cache</samp> if not given.
</p>
<p>If no directory is given (or it is the empty matrix), a cache for built-in
functions, operators, and keywords is generated.
</p>
<p><strong>See also:</strong> <a href="#XREFdoc_005fcache_005ffile">doc_cache_file</a>, <a href="#XREFlookfor">lookfor</a>, <a href="Manipulating-the-Load-Path.html#XREFpath">path</a>.
</p></dd></dl>
<a name="XREFget_005fhelp_005ftext"></a><dl>
<dt><a name="index-get_005fhelp_005ftext"></a><em>[<var>text</var>, <var>format</var>] =</em> <strong>get_help_text</strong> <em>(<var>name</var>)</em></dt>
<dd><p>Return the raw help text of function <var>name</var>.
</p>
<p>The raw help text is returned in <var>text</var> and the format in <var>format</var>
The format is a string which is one of <code>"texinfo"</code>,
<code>"html"</code>, or <code>"plain text"</code>.
</p>
<p><strong>See also:</strong> <a href="#XREFget_005fhelp_005ftext_005ffrom_005ffile">get_help_text_from_file</a>.
</p></dd></dl>
<a name="XREFget_005fhelp_005ftext_005ffrom_005ffile"></a><dl>
<dt><a name="index-get_005fhelp_005ftext_005ffrom_005ffile"></a><em>[<var>text</var>, <var>format</var>] =</em> <strong>get_help_text_from_file</strong> <em>(<var>fname</var>)</em></dt>
<dd><p>Return the raw help text from the file <var>fname</var>.
</p>
<p>The raw help text is returned in <var>text</var> and the format in <var>format</var>
The format is a string which is one of <code>"texinfo"</code>,
<code>"html"</code>, or <code>"plain text"</code>.
</p>
<p><strong>See also:</strong> <a href="#XREFget_005fhelp_005ftext">get_help_text</a>.
</p></dd></dl>
<a name="XREFget_005ffirst_005fhelp_005fsentence"></a><dl>
<dt><a name="index-get_005ffirst_005fhelp_005fsentence"></a><em><var>text</var> =</em> <strong>get_first_help_sentence</strong> <em>(<var>name</var>)</em></dt>
<dt><a name="index-get_005ffirst_005fhelp_005fsentence-1"></a><em><var>text</var> =</em> <strong>get_first_help_sentence</strong> <em>(<var>name</var>, <var>max_len</var>)</em></dt>
<dt><a name="index-get_005ffirst_005fhelp_005fsentence-2"></a><em>[<var>text</var>, <var>status</var>] =</em> <strong>get_first_help_sentence</strong> <em>(…)</em></dt>
<dd><p>Return the first sentence of a function’s help text.
</p>
<p>The first sentence is defined as the text after the function declaration
until either the first period (".") or the first appearance of two
consecutive newlines ("\n\n"). The text is truncated to a maximum length of
<var>max_len</var>, which defaults to 80. If the text must be truncated the last
three characters of the text are replaced with <code>"..."</code> to indicate
that more text was available.
</p>
<p>The optional output argument <var>status</var> returns the status reported by
<code>makeinfo</code>. If only one output argument is requested, and <var>status</var>
is nonzero, a warning is displayed.
</p>
<p>As an example, the first sentence of this help text is
</p>
<div class="example">
<pre class="example">get_first_help_sentence ("get_first_help_sentence")
-| ans = Return the first sentence of a function's help text.
</pre></div>
</dd></dl>
<hr>
<div class="header">
<p>
Next: <a href="Command-Line-Editing.html#Command-Line-Editing" accesskey="n" rel="next">Command Line Editing</a>, Previous: <a href="Quitting-Octave.html#Quitting-Octave" accesskey="p" rel="prev">Quitting Octave</a>, Up: <a href="Getting-Started.html#Getting-Started" accesskey="u" rel="up">Getting Started</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
</body>
</html>
