Getting Started

Getting Started with MATLAB

There are several different ways to access online information about MATLAB functions.

The help command
The help window
The MATLAB Help Desk
Online reference pages
Link to The MathWorks, Inc.

The help command is the most basic way to determine the syntax and behavior of a particular function. Information is displayed directly in the command window. For example

help magic

prints

MAGIC  Magic square.
    MAGIC(N) is an N-by-N matrix constructed from
    the integers 1 through N^2 with equal row,
    column, and diagonal sums.

NOTE
MATLAB online help entries use uppercase characters for the function and variable names to make them stand out from the rest of the text. When typing function names, however, always use the corresponding lowercase characters because MATLAB is case sensitive and all function names are actually in lowercase.

All the MATLAB functions are organized into logical groups, and MATLAB's directory structure is based on this grouping. For example, all the linear algebra functions reside in the matfun directory. To list the names of all the functions in that directory, with a brief description of each:

help matfun

Matrix functions - numerical linear algebra.

Matrix analysis.
  norm        - Matrix or vector norm.
  normest     - Estimate the matrix 2-norm
...

The command

help

by itself lists all the directories, with a description of the function category each represents:

matlab/general       
matlab/ops           
...

The Help Window

The MATLAB help window is available on PCs and Macs by selecting the Help Window option under the Help menu, or by clicking the question mark on the menu bar. It is also available on all computers by typing

helpwin

To use the help window on a particular topic, type

helpwin topic

The help window gives you access to the same information as the help command, but the window interface provides convenient links to other topics.

The lookfor Command

The lookfor command allows you to search for functions based on a keyword. It searches through the first line of help text, which is known as the H1 line, for each MATLAB function, and returns the H1 lines containing a specified keyword. For example, MATLAB does not have a function named inverse. So the response from

help inverse

inverse.m not found.

But

lookfor inverse

finds over a dozen matches. Depending on which toolboxes you have installed, you will find entries like

INVHILB Inverse Hilbert matrix.
ACOSH   Inverse hyperbolic cosine.
ERFINV  Inverse of the error function.
INV     Matrix inverse.
PINV    Pseudoinverse.
IFFT    Inverse discrete Fourier transform.
IFFT2   Two-dimensional inverse discrete Fourier transform.
ICCEPS  Inverse complex cepstrum.
IDCT    Inverse discrete cosine transform.

Adding -all to the lookfor command, as in

lookfor -all

searches the entire help entry, not just the H1 line.

The Help Desk

The MATLAB Help Desk provides access to a wide range of help and reference information stored on a disk or CD-ROM in your local system. Many of the underlying documents use HyperText Markup Language (HTML) and are accessed with an Internet Web browser such as Netscape or Microsoft Explorer. The Help Desk process can be started on PCs and Macs by selecting the Help Desk option under the Help menu, or, on all computers, by typing

helpdesk

All of MATLAB's operators and functions have online reference pages in HTML format, which you can reach from the Help Desk. These pages provide more details and examples than the basic help entries. HTML versions of other documents, including this manual, are also available. A search engine, running on your own machine, can query all the online reference material.

Printing Online Reference Pages

Versions of the online reference pages are also available in Portable Document Format (PDF) through the Help Desk. These pages are processed by Adobe's Acrobat reader. They reproduce the look and feel of the printed page, complete with fonts, graphics, formatting, and images. This is the best way to get printed copies of reference material.

Link to the MathWorks

If your computer is connected to the Internet, the Help Desk provides a connection to The MathWorks, the home of MATLAB. You can use electronic mail to ask questions, make suggestions, and report possible bugs. You can also use the Solution Search Engine at The MathWorks Web site to query an up-to-date data base of technical support information.

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