# 5. Commands

In this lesson you will learn:

- Commands for managing the work session.
- Commands for working with the system.
- Input and output commands.
- Vector, Matrices and Array commands.
- Plotting commands.

In our third lecture about MATLAB syntax we simply overview the ‘commands’ for managing the work session. Now we discuss all the commands one by one.

**1. Commands for managing the work session:**

The lists of commonly used general MATLAB commands are:

clc | Clears the Command window |

clear | Removes all variables from memory |

clear v1 v2 | Removes the variables v1 and v2 from memory. |

exist ( ‘ var ‘ ) | Determines if a file or variable exists having the name ‘var’ |

quit | Stops MATLAB |

who | Lists the variables currently in memory |

whos | Lists the current variables and sizes, and indicates if they have imaginary parts |

exit | Exit MATLAB |

global | Declares variables to be global |

help | Searches for a help topic |

lookfor | Searches help entries for a keyword |

**2. 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. The table shows some commonly used system-related commands:

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 |

**3. Input and output commands:**

Following are the input and output related commands in MATLAB:

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 |

This picture show you how ‘DISP’ command works.

- The black line shows how to simple display string.
- The red line shows how to display two scalars on one line.
- The yellow line simply display the transpose of vector x and y. Note ( ‘ ) symbol with x’ and y’ is used to taking transpose.
- The blue line shows how to display string along with numeric data or stored value.

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

%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 short | Display up to Four decimal digits (default). |

format long | Display up to 16 decimal digits. |

format short e | Display up to Five digits plus exponent. |

format long e | Display up to 16 digits plus exponents. |

format bank | Display up to Two decimal digits. |

format + | Display up to Positive, negative, or zero. |

format rat | Display up to Rational approximation. |

format compact | Display up to Suppresses some line feeds. |

formatloose | Display up to Resets to less compact display mode. |

**4. Vector, Matrices and Array commands:**

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

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. |

**5. Plotting Commands:**

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

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. |

ploar | Creates polar plot. |

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

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

stairs | Creates stairs plot. |

stem | Creates stem plot. |

So this is the end of our fifth lesson. Please share this article if you like and do not forget to comment.