Getting Started

Getting Started with MATLAB

So far, you have been using the MATLAB command line, typing commands and expressions, and seeing the results printed in the command window. This section describes a few ways of altering the appearance of the command window. If your system allows you to select the command window font or typeface, we recommend you use a fixed width font, such as Fixedsys or Courier, to provide proper spacing.

The format Command

The format command controls the numeric format of the values displayed by MATLAB. The command affects only how numbers are displayed, not how MATLAB computes or saves them. Here are the different formats, together with the resulting output produced from a vector x with components of different magnitudes.

x = [4/3 1.2345e-6]

format short

   1.3333    0.0000

format short e

   1.3333e+000  1.2345e-006

format short g

   1.3333  1.2345e-006

format long

   1.33333333333333   0.00000123450000

format long e

   1.333333333333333e+000    1.234500000000000e-006

format long g

   1.33333333333333               1.2345e-006

format bank

   1.33          0.00

format rat

   4/3          1/810045

format hex
 
   3ff5555555555555   3eb4b6231abfd271

If the largest element of a matrix is larger than 10³ or smaller than 10^-3,
MATLAB applies a common scale factor for the short and long formats.

In addition to the format commands shown above

format compact

suppresses many of the blank lines that appear in the output. This lets you view more information on a screen or window. If you want more control over the output format, use the sprintf and fprintf functions.

Suppressing Output

If you simply type a statement and press Return or Enter, MATLAB automatically displays the results on screen. However, if you end the line with a semicolon, MATLAB performs the computation but does not display any output. This is particularly useful when you generate large matrices. For example

A = magic(100);

Long Command Lines

If a statement does not fit on one line, use three periods, ..., followed by Return or Enter to indicate that the statement continues on the next line. For example

s = 1 -1/2 + 1/3 -1/4 + 1/5 - 1/6 + 1/7 ...
      - 1/8 + 1/9 - 1/10 + 1/11 - 1/12;

Blank spaces around the =, +, and - signs are optional, but they improve readability. The maximum number of characters allowed on a single line is 4096.

Command Line Editing

Various arrow and control keys on your keyboard allow you to recall, edit, and reuse commands you have typed earlier. For example, suppose you mistakenly enter

rho = (1 + sqt(5))/2

You have misspelled sqrt. MATLAB responds with

Undefined function or variable 'sqt'.

Instead of retyping the entire line, simply press the

key. The misspelled command is redisplayed. Use the

key to move the cursor over and insert the missing r. Repeated use of the

key recalls earlier lines. Typing a few characters and then the

key finds a previous line that begins with those characters.

The list of available command line editing keys is different on different computers. Experiment to see which of the following keys is available on your machine. (Many of these keys will be familiar to users of the EMACS editor.)

	`ctrl-p`	Recall previous line
	`ctrl-n`	Recall next line
	`ctrl-b`	Move back one character
	`ctrl-f`	Move forward one character
`ctrl-`	`ctrl-`r	Move right one word
`ctrl-`	`ctrl-`l	Move left one word
home	`ctrl-a`	Move to beginning of line
end	`ctrl-e`	Move to end of line
esc	`ctrl-u`	Clear line
del	`ctrl-d`	Delete character at cursor
backspace	`ctrl-h`	Delete character before cursor
	`ctrl-k`	Delete to end of line

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