5. Commands

In this lesson you will learn:

  1. Commands for managing the work session.
  2. Commands for working with the system.
  3. Input and output commands.
  4. Vector, Matrices and Array commands.
  5. 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.

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

Disp command

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.
print 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.

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