02_GENN004m_ArithmeticOperations

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GENN004: Introduction to Computers 09-Feb-

Arithmetic Operations


Variables, Assignment, Expressions

Outline

Variables

Assignment Statements

Arithmetic Operators

Built-in MATLAB Functions


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The Command Window The Command

History Window

The Start Button

Workspace

Browser

Path Browser

Help Browser

Function Browser

MATLAB Desktop

The prompt

What are the usages of these items?

Try it and take notes

Current Directory

User Input

(What you typed)

Calculation Results

(What MATLAB computed from your statement)

Command Window


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Variables

Variable: a named space for storing a value

radius

area

Valid names start with a letter, can contain

digits.

Use meaningful variable names.

MATLAB is case sensitive (area and Area are different)

Assignment Statement

Variable: a named space for storing a value

sum

Assignment: putting a value into a variable

Assignment operator: =

An assignment statement: r= 2*4.5

Expression on Right Hand Side is evaluatedbefore the assignment operation


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Assignment Statement

Expression on rhs is evaluated before the

assignment operation

Examples:

x= 2*3.14

y= 1+x

z= 4^2 cos(y)

Any variable on the rhs must be initialized

Scalar vs Array Scalar: indicates a variable that holds only a single

value at a time.

This is compared to an array, which holds many values atonce

Array: is an indexed grouping of values, addressed withsubscripts

B = [1.0 2.0 3.0] creates a 1 x 3 row array/vector

length(vec): Returns length (# of elements) of vector

length(B) returns 3

A = [10, 20, 30, 40, 50]

A(1)=10

A(2)=20

A(3)=30


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Operators

+ Addition

- Subtraction

* Multiplication

/ Division (divided by e.g., 10/5 is 2)

\ Division (divided into e.g., 5\10 is 2)

^ Exponentiation (e.g., 5^2 is 25)

Operators Precedence

( ) parentheses

^ exponentiation

- negation

*,/,\ multiplication and division

+, - addition and subtraction


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Etter/Ingber

Arithmetic Operation Examples

What the results would be for the followingexpressions (do it by hand then test it onMATLAB):

1. a = 3 + 5 / 10

2. a = ( 3 + 5 ) / 10

3. a = 3 + 5 / 10 * 3

4. a = 3/2 5 / 10

5. a = 3 5/26. a = ((3+5)/((3+2)*2))

Etter/Ingber

Arithmetic Operations Examples

Write the MATLAB expression to evaluate the followingequations: Assume x=3, y=5, z=10 (do it by hand thentest it on MATLAB)

;53

)32(

;543

;3

2

22

+

+=

+

++=

+=

z

yxa

yx

yzxa

z

yxa


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MATLAB built-in functions

x= 25;

y=cos(x);

a=sqrt(x);

z=rem(13,5);

Function name

Arguments (values) passed to the function

- For more functions, check the Function Browser

- Or type help elfun to show a list of the elementary mathfunctions- Practice: Find out what the rounding functionsfloor, ceil,

and rounddo.

Functions Examples

Evaluate the following expressions (do it by handthen test it on MATLAB):

1. floor(-2.6) ceil(-2.6)

2. abs(-10*2.5) abs(-2^5)

3. floor(ceil(10.8)) ceil(floor(10.8))

4. rem(10,3) rem(3,10)5. round(10.4) round(10.6)

6. fix(10.4) fix(10.6)

02_GENN004m_ArithmeticOperations

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