Matlab Introduction

INTRODUCTION TO MATLAB Matlab is a product of The Math Works, Inc. It is an outstanding software package for scientific and engineering computations. Matlab enables us to solve many advanced numerical problems fast and efficiently. It provides an interactive environment with hundreds of built-in functions for technical computation, graphics, animation. Matlab is both a computer programming language and a software environment for using that language effectively. The name MATLAB stands for MATRIX LABORATORY. Matlab is a high-level language whose basic data type is a matrix that does not require dimensioning. It has a large collection of toolboxes in a variety of domains. Some examples of Matlab toolboxes are control system, signal processing, image processing, and system identification. The toolboxes consist of functions that can be used to perform computations in a specific domain. Matlab has many advantages compared to conventional computer languages for solvimg technical problems. Matlab is an interactive system whose basic data type is a matrix that does not require dimensioning. The software package has been commercially available since 1984 and is now considered as a standard tool at most universities and industries worldwide.

MATLAB WINDOWS 1. Command window: This is the main window. It is characterized by Matlab command prompt’>>’. All commands, including those for running user-written programs, are typed in this window at the Matlab prompt. 2. Graphics Window: The output of all graphics commands typed are flushed into the graphics or figure window. 3. Edit Window: This is a place to create, write, edit and save programs in files called Mfiles. Any text editor can be used to carry out these tasks. MATLAB COMMANDS General-purpose commands General information helpbrowser

- Bring up the help browser.

doc

- Complete on-line help, displayed in the help browser.

help

- M-file help, displayed at the command line.

helpwin

- M-file help displayed in the help browser.

lookfor

- Search all M-files for keyboard.

syntax

- Help on Matlab command syntax.

Managing the workspace workspace

- Display Workspace browser, a GUI for managing the workspace.

clear

- Clear variables and functions from memory.

save

- Save workspace variables to disk.

Matlab

- Loads the program matlab into your workspace.

clear x

- Deletes the matrix x from active workspace.

Elementary math functions Trignometric sin

- sine

sinh

- hyperbolic sine

asin

- inverse sin

asinh

- inverse hyperbolic sine

cos

- cosine

cosh

- hyperbolic cosine

aos

- inverse cosine

aosh

- inverse hyperbolic cosine

tan

- tangent

tanh

- hyperbolic tangent

sec

- secant

sech

- hyperbolic secant

csc

- cosecant

cot

- cotangent

coth

- hyperbolic cotangent

Exponential exp

- exponential

log

- natural logarithm

sqrt

- square root

Complex abs

- absolute value

angle

- phase angle

complex

- construct complex data

conj

- complex conjugate

real

- complex real part

imag

- complex imaginary part

Rounding and remainder fix

- round toward zero

round

- round towards nearest integer

mod

- modulus

rem

- remainder

sign

- signum

Commands useful in plotting semilogx(x,y) - plots log(x) vs. y loglog(x,y)

- plots log(x) vs log(y)

title(‘text’)

- places a title at the top of graphics plot

xlabel(‘text’) - writes text beneath the x-axis of a plot axis

- controls axis scaling and appearance

subplot

- creates axes in tiled positions

Data analysis commands max(x)

- returns the maximum value of the elements in a vector or if x is a matrix, returns a row vector whose elements are the maximum values from each respective column of the matrix

min(x)

- returns the minimum value of x

mean(x)

- returns the mean value of x

sum(x)

- returns the sum of the elements of a vector or if x is a matrix, returns the sum of the elements from each respective column of the matrix.

sort(x)

- sort the values in the vector x or the columns of a matrix and places them in ascending order.

hist(x)

- plots a histogram of the elements of the vector x

Special matrices zeros(n)

- creates an n × n matrix whose elements are zero

zeros(m,n)

- creates an m-row, n-column matrix of zeros

ones(n)

- creates an n × n square matrix whose elements are 1’s

ones(m,n)

- creates an m × n matrix whose elements are 1’s

eye(n)

- creates an n × n identity matrix with 1’s on the diagonal

Miscellaneous commands length(x)

- returns the number of elements in a vector

size(x)

- returns the size m(rows) and n(columns) of matrix x

rand

- returns the random number between 0 and 1

rand(A)

- returns a matrix of size A of random numbers