help

Help about an LME function.

Syntax

help functionname
help 'operator'
help
help(str, fd=fd)
b = help(str)

Description

help functionname displays a help message about function whose name is functionname. help 'operator' displays a help message about an operator. For methods (functions for arguments of a specific class), the class should be specified as class::method, except for constructors where both class and class::class are recognized. Without argument, help displays a message about the help command itself.

For user functions, help uses the first comment which immediately follows the function header. The comment may be a continuous set of lines beginning with % or //, or a single block of lines delimited with /* and */. Lines which contain /* and */ cannot have any other character, not even spaces. Alternatively for user functions, or for built-in or extension functions, the help text is found in files with suffix ".hlp" in the same folders as libraries. For functions unknown to LME (such as functions defined in libraries which have not been loaded with use), help searches in file other.hlp, which typically includes each library hlp files with includeifexists statements.

If no matching function is found, help has the same effect as lookfor, i.e. it proposes a list of functions whose short description contains the string passed as argument (or just the method name if the argument has the syntax class::method).

A named argument fd can specify the output channel; in that case, the command syntax cannot be used.

With an output argument, help returns true if help is found for its input argument, false otherwise. Help is not displayed. The lookfor fallback is not attempted.

Examples

Help about function sin:

help sin
Sine.

SYNTAX
y = sin(x)
...

Help about operator +:

help '+'
Addition.

SYNTAX
x + y
M1 + M2
...

Source code of function dctmtx with its help comment block:

 function T = dctmtx(n)
 /*
 Discrete cosine transform matrix.
 
 SYNTAX
 T = dctmtx(n)
 
 DESCRIPTION
 dctmtx(n) returns an n-by-n square matrix T such that
 Y=T*y is the discrete cosine transform of the columns
 ...
 */
     T = [repmat(1/sqrt(n),1,n); ...
         sqrt(2/n)*cos(pi/(2*n)*repmat(1:2:2*n,n-1,1)...
             .*repmat((1:n-1)',1,n))];

See also

lookfor, which

lookfor

Search functions.

Syntax

lookfor str
lookfor('str')
lookfor('str', fd=fd)

Description

lookfor str searches the characters str in the short description of all commands and functions and displays all the matches. Case is ignored. If str contains spaces or non-alphanumeric characters, the syntax lookfor('str') must be used.

A named argument fd can specify the output channel; in that case, the command syntax cannot be used.

Example

lookfor arc
  lookfor   Search functions.
  acos      Arc cosine.
  asin      Arc sine.
  atan      Arc tangent.

See also

help