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MATLAB Tutorial 1-Machine Learning-Lecture Handout, Exercises of Machine Learning

Pakistan Institute of Engineering and Applied Sciences, Islamabad (PIEAS)Machine Learning

This lecture notes was distributed for Machine Learning course by Pakistan Institute of Engineering and Applied Sciences, Islamabad (PIEAS). Its main points are: MATLAB, Matrices, Vectors, Variables, Subscript, Notation, Colon, Complex, Numbers, Strings, Polynomials

Typology: Exercises

2011/2012

Uploaded on 07/19/2012

zaraa 🇵🇰

6 documents

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Dr. Hanif Durad 2

Lecture Outline (1/2)

Basic MATLAB Operations

Starting MATLAB

Using MATLAB as a calculator

Introduction to variables and functions

Matrices and Vectors: All variables are matrices.

Creating matrices and vectors

Subscript notation

Colon notation

Discover Exercises of Machine Learning Pakistan Institute of Engineering and Applied Sciences, Islamabad (PIEAS)

Partial preview of the text

Download MATLAB Tutorial 1-Machine Learning-Lecture Handout and more Exercises Machine Learning in PDF only on Docsity!

Dr. Hanif Durad

Lecture Outline (1/2)

^ Basic MATLAB Operations^ 

Starting MATLAB  Using MATLAB as a calculator  Introduction to variables and functions

^ Matrices and Vectors: All variables are matrices.^ 

Creating matrices and vectors  Subscript notation  Colon notation

Dr. Hanif Durad

Lecture Outline (2/2)

^ Additional Types of Variables^ ^

Complex numbers  Strings  Polynomials

^ Working with Matrices and Vectors^ ^

Some basic linear algebra  Vectorized operations  Array operators

^ Managing the Interactive Environment ^ Plotting

MATLAB Desktop (1/2)

MATLAB Desktop (2/2)  The desktop provides different ways ofinteracting with MATLAB ^ Entering commands in the command window ^ Viewing values stored in variables ^ Editing statements in MATLAB functions andscripts ^ Creating and annotating plots

Dr. Hanif Durad

MATLAB as a Calculator (2/2)

^ Define and use variables>> a = 5a =^5 >> b = 6b =^6 >> c = b/ac =1.

Dr. Hanif Durad

Built-in Variables (1/2)

pi (=

π) and ans are a built-in variables

>> pians =3.1416>> sin(ans/4)ans =0.7071Note: There is no “degrees” mode. All angles are measuredin radians.

Dr. Hanif Durad

Built-in Functions

^ Many standard mathematical functions, such as sin, cos, log, andlog10, are built-in>> log(256)

log(x) computes the natural logarithm of x

ans =5.5452>> log10(256)

log10(x) is the base 10 logarithm

ans =2.4082>> log2(256)

log2(x) is the base 2 logarithm

ans = 8

Ways to Get Help

Dr. Hanif Durad

^ Use on-line help to request info on a specific function>> help sqrt ^ In MATLAB version 6 and later the doc functionopens the on-line version of the manual. This is veryhelpful for more complex commands.>> doc plot ^ Use lookfor to find functions by keywords>> lookfor functionName

^ The help browser opens when you type a doc command:>> doc plot

On-line Help (2/2)

Looking for Functions

Dr. Hanif Durad

^ Syntax:lookfor stringsearches first line of function descriptions for “string”.Example:>> lookfor cosineproducesACOS

Inverse cosine. ACOSH

Inverse hyperbolic cosine. COS

Cosine. COSH

Hyperbolic cosine.

Suppress Output with Semicolon(1/2)

Dr. Hanif Durad

^ Results of intermediate steps can be suppressed withsemicolons.Example: Assign values to x, y, and z, but only displaythe value of z in the command window:>> x = 5;>> y = sqrt(59);>> z = log(y) + x^0.

z =3.

Dr. Hanif Durad

^ Type variable name and omit the semicolon to print the value ofa variable (that is already defined)>> x = 5;>> y = sqrt(59);>> z = log(y) + x^0.25z =3.5341>> yy =7.

( = log(sqrt(59)) + 5^0.25 ) Suppress Output with Semicolon(2/2)

MATLAB Variables Names

Legal variable names:^ ^

Begin with one of a–z or A–Z  Have remaining characters chosen from a–z, A–Z, 0–9, or  Have a maximum length of 31 characters  Should not be the name of a built-in variable, built-in function, or  user-defined function

^ Examples:^ ^

xxxxxxxxx  pipeRadius  widgets_per_box  mySum  mysum

^ Note: mySum and mysum are differentvariables. MATLAB is case sensitive.

Built-in MATLAB Variables(1/2)

Dr. Hanif Durad

Name

Meaning ans^

value of an expression when that expression is not assignedto a variable eps^

floating point precision pi^

π, (3.141492.. .) realmax

largest positive floating point number realmin

smallest positive floating point number Inf^

∞, a number larger than realmax, the result of evaluating 1/0. NaN^

not a number, the result of evaluating 0/

MATLAB Tutorial 1-Machine Learning-Lecture Handout, Exercises of Machine Learning

Related documents

Partial preview of the text

Download MATLAB Tutorial 1-Machine Learning-Lecture Handout and more Exercises Machine Learning in PDF only on Docsity!

Lecture Outline (1/2)

^ Basic MATLAB Operations^ 

Starting MATLAB  Using MATLAB as a calculator  Introduction to variables and functions

^ Matrices and Vectors: All variables are matrices.^ 

Creating matrices and vectors  Subscript notation  Colon notation

Lecture Outline (2/2)

^ Additional Types of Variables^ ^

^ Working with Matrices and Vectors^ ^

^ Managing the Interactive Environment ^ Plotting

MATLAB Desktop (1/2)

MATLAB Desktop (2/2)  The desktop provides different ways ofinteracting with MATLAB ^ Entering commands in the command window ^ Viewing values stored in variables ^ Editing statements in MATLAB functions andscripts ^ Creating and annotating plots

MATLAB as a Calculator (2/2)

^ Define and use variables>> a = 5a =^5 >> b = 6b =^6 >> c = b/ac =1.

Built-in Variables (1/2)

pi (=

π) and ans are a built-in variables

>> pians =3.1416>> sin(ans/4)ans =0.7071Note: There is no “degrees” mode. All angles are measuredin radians.

Built-in Functions

Ways to Get Help

^ Use on-line help to request info on a specific function>> help sqrt ^ In MATLAB version 6 and later the doc functionopens the on-line version of the manual. This is veryhelpful for more complex commands.>> doc plot ^ Use lookfor to find functions by keywords>> lookfor functionName

On-line Help (2/2)

Looking for Functions

^ Syntax:lookfor stringsearches first line of function descriptions for “string”.Example:>> lookfor cosineproducesACOS

Suppress Output with Semicolon(1/2)

^ Results of intermediate steps can be suppressed withsemicolons.Example: Assign values to x, y, and z, but only displaythe value of z in the command window:>> x = 5;>> y = sqrt(59);>> z = log(y) + x^0.

z =3.

MATLAB Variables Names

Legal variable names:^ ^

^ Examples:^ ^

Built-in MATLAB Variables(1/2)