Functions should have help text so that people know how to use it.

Guidelines

First sentence

The first sentence of help text should start with a statement that is like a command. For example, the first sentence of hist:

Produce histogram counts or plots.         # good
Produces histogram counts or plots.        # bad
hist produces histogram counts or plots.   # bad

Manual reference

When submitting a function to Octave, a tag for the docstring should be added to some appropriate place in one of the manual's .txi source files (they are all in doc/interpreter/). Find the most appropriate section in the manual and add the following with the related functions:

Code: adding tag for function help text in Octave's manual

+@DOCSTRING(function_name)

If appropriate, also write some text about the function on the manual for better inclusion into the manual.

Sentence spacing

The typographical convention in Octave is to use two full spaces after a period that ends a sentence. For example:

there is no correct for sentence spacing.  But we need a convention # good
there is no correct for sentence spacing. But we need a convention  # bad

TexInfo

This is the preferred format for help text. There is also a comprehensive TexInfo manual.

Examples

If you give a code example in the documentation written in Texinfo with the @example environment, you should be aware that the text within such an environment will not be wrapped. It is recommended that you keep the lines short enough to fit on pages in the generated pdf or ps documents. That means, keep the lines of examples under 60 characters.

Octave specific macros

deftypefn

This environment will enclose the function help text. It takes as argument the type of function. Typical values are

Function File -- for functions in .m files
Loadable Function -- for functions in .oct files
Accessor method
Class property

Besides this environment there is also the alternative deftypenx for alternative forms. Typically these are mentioned at the top of the help text, right after the deftypen although this is not really necessary. Cases where it's acceptable to have them on other sections would be methods on the help text of a class constructor, since they will not always be on a separate file.

Formatting

Formulas

Do not use the example environment to insert formulas, consider using @verbatim instead.

@verbatim
           E[Z(i,k) ]
IRL(k) =  ------------
              V(i)
@end verbatim

However, this will never print as a nice looking mathematical formula that TeX is known for. It is possible to have Tex formulas but then they won't be displayed on HTML or Info (Octave help) so the following can be done:

@tex
\def\frac#1#2{{\begingroup#1\endgroup\over#2}}
$$ IRL(k) = \frac{E[Z(i,k)]}{V(i)} $$
@end tex
@ifnottex
@verbatim
           E[Z(i,k) ]
IRL(k) =  ------------
              V(i)
@end verbatim
@end ifnottex

Plain-tex missing macros

When compared to LaTeX, plain TeX is missing some very useful macros for including mathematical notation. The following is a list of their definitions which can be added on a as needed basis:

frac

\def\frac#1#2{{\begingroup#1\endgroup\over#2}}

Special inserts

Escape characters

To escape characters in TexInfo, use the character @. Only the characters @, { and } need to be escaped.

@@ stands for a single @ (do not put braces after an @@ command)
@{ stands for a single {
@} stands for a single }

In certain contexts (such as @acronym or @xref), commas may need to be escaped. In such situations, use @comma{}.

Ellipsis (...)

Ellipsis are frequently used in octave help text, specially when defining a function API. Use the @dots{} rather than three dots.

@deftypefn {Function File} {} imhist (@var{I})
@deftypefnx {Function File} {[@var{counts}, @var{x}] =} imhist (@dots{})

Matlab

Sometimes it is need to mention matlab in the help text. For example, to mention that a weird behavior needs to be kept for matlab compatibility. In such case, small caps should be used. For example, the following is used in the length help text:

For matrix objects, the length is the number of rows or columns, whichever is
greater (this odd definition is used for compatibility with @sc{matlab}).

Help text style guide

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