# MATLAB - Commands

MATLAB is an interactive program for numerical computation and data visualization. You can enter a command by typing it at the MATLAB prompt '>>' on the **Command Window**.

In this section, we will provide lists of commonly used general MATLAB commands.

## Commands for Managing a Session

MATLAB provides various commands for managing a session. The following table provides all such commands:

Command | Purpose |
---|---|

clc | Clears command window. |

clear | Removes variables from memory. |

exist | Checks for existence of file or variable. |

global | Declares variables to be global. |

help | Searches for a help topic. |

lookfor | Searches help entries for a keyword. |

quit | Stops MATLAB. |

who | Lists current variables. |

whos | Lists current variables (long display). |

## Commands for Working with the System

MATLAB provides various useful commands for working with the system, like saving the current work in the workspace as a file and loading the file later.

It also provides various commands for other system-related activities like, displaying date, listing files in the directory, displaying current directory, etc.

The following table displays some commonly used system-related commands:

Command | Purpose |
---|---|

cd | Changes current directory. |

date | Displays current date. |

delete | Deletes a file. |

diary | Switches on/off diary file recording. |

dir | Lists all files in current directory. |

load | Loads workspace variables from a file. |

path | Displays search path. |

pwd | Displays current directory. |

save | Saves workspace variables in a file. |

type | Displays contents of a file. |

what | Lists all MATLAB files in the current directory. |

wklread | Reads .wk1 spreadsheet file. |

## Input and Output Commands

MATLAB provides the following input and output related commands:

Command | Purpose |
---|---|

disp | Displays contents of an array or string. |

fscanf | Read formatted data from a file. |

format | Controls screen-display format. |

fprintf | Performs formatted writes to screen or file. |

input | Displays prompts and waits for input. |

; | Suppresses screen printing. |

The **fscanf** and **fprintf** commands behave like C scanf and printf functions. They support the following format codes:

Format Code | Purpose |
---|---|

%s | Format as a string. |

%d | Format as an integer. |

%f | Format as a floating point value. |

%e | Format as a floating point value in scientific notation. |

%g | Format in the most compact form: %f or %e. |

\n | Insert a new line in the output string. |

\t | Insert a tab in the output string. |

The format function has the following forms used for numeric display:

Format Function | Display up to |
---|---|

format short | Four decimal digits (default). |

format long | 16 decimal digits. |

format short e | Five digits plus exponent. |

format long e | 16 digits plus exponents. |

format bank | Two decimal digits. |

format + | Positive, negative, or zero. |

format rat | Rational approximation. |

format compact | Suppresses some line feeds. |

format loose | Resets to less compact display mode. |

## Vector, Matrix and Array Commands

The following table shows various commands used for working with arrays, matrices and vectors:

Command | Purpose |
---|---|

cat | Concatenates arrays. |

find | Finds indices of nonzero elements. |

length | Computes number of elements. |

linspace | Creates regularly spaced vector. |

logspace | Creates logarithmically spaced vector. |

max | Returns largest element. |

min | Returns smallest element. |

prod | Product of each column. |

reshape | Changes size. |

size | Computes array size. |

sort | Sorts each column. |

sum | Sums each column. |

eye | Creates an identity matrix. |

ones | Creates an array of ones. |

zeros | Creates an array of zeros. |

cross | Computes matrix cross products. |

dot | Computes matrix dot products. |

det | Computes determinant of an array. |

inv | Computes inverse of a matrix. |

pinv | Computes pseudoinverse of a matrix. |

rank | Computes rank of a matrix. |

rref | Computes reduced row echelon form. |

cell | Creates cell array. |

celldisp | Displays cell array. |

cellplot | Displays graphical representation of cell array. |

num2cell | Converts numeric array to cell array. |

deal | Matches input and output lists. |

iscell | Identifies cell array. |

## Plotting Commands

MATLAB provides numerous commands for plotting graphs. The following table shows some of the commonly used commands for plotting:

Command | Purpose |
---|---|

axis | Sets axis limits. |

fplot | Intelligent plotting of functions. |

grid | Displays gridlines. |

plot | Generates xy plot. |

Prints plot or saves plot to a file. | |

title | Puts text at top of plot. |

xlabel | Adds text label to x-axis. |

ylabel | Adds text label to y-axis. |

axes | Creates axes objects. |

close | Closes the current plot. |

close all | Closes all plots. |

figure | Opens a new figure window. |

gtext | Enables label placement by mouse. |

hold | Freezes current plot. |

legend | Legend placement by mouse. |

refresh | Redraws current figure window. |

set | Specifies properties of objects such as axes. |

subplot | Creates plots in subwindows. |

text | Places string in figure. |

bar | Creates bar chart. |

loglog | Creates log-log plot. |

polar | Creates polar plot. |

semilogx | Creates semilog plot. (logarithmic abscissa). |

semilogy | Creates semilog plot. (logarithmic ordinate). |

stairs | Creates stairs plot. |

stem | Creates stem plot. |