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№1 слайд
Содержание слайда: Mathematics for Computing
2016-2017
№2 слайд
Содержание слайда: Topics 2016-17
Number Representation
Logarithms
Logic
Set Theory
Relations & Functions
Graph Theory
№3 слайд
Содержание слайда: Assessment
In Class Test (Partway through term, 31/10)
(20% of marks)
‘Homework’ (3 parts for 10% of marks)
Two hour unseen examination in May/June 2017
(70% of marks)
№4 слайд
Содержание слайда: Lecture / tutorial plans
Lecture every week 18:00 for 18:10 start. 1 – 2½ hours (with break)
Tutorials (problems and answers) one week in two (~1½ hours)
Compulsory In-Class Test, October 31st
Lecture Notes etc. will appear on Moodle
Class split in two rooms
№5 слайд
Содержание слайда: Provisional Timetable
№6 слайд
Содержание слайда: Course Textbook
Schaum’s Outlines Series
Essential Computer Mathematics
Author: Seymour Lipschutz
ISBN 0-07-037990-4
№7 слайд
Содержание слайда: Maths Support
http://www.bbk.ac.uk/business/current-students/learning-co-ordinators/eva-szatmari
See separate powerpoint file.
№8 слайд
Содержание слайда: Lecture 1
Rule 1
Communication is not easy,
How do you tell a computer what to do?
№9 слайд
Содержание слайда: Welcome
Rule 1
We want to get the computer to do NEW complicated things
We start by learning the basics of its language, Numerical Representation, Logic …
№10 слайд
Содержание слайда: Memory for numbers
We don’t know how our memory stores numbers
We know how a computer does (we designed it)
Full glass is 1, empty is 0
№11 слайд
Содержание слайда: Great, we know how to store 1 and 0 in the computer memory
Great, we know how to store 1 and 0 in the computer memory
How do we store 0,1,2,3?
We use two cups!
№12 слайд
Содержание слайда: If we want extra numbers we add an extra cup!
If we want extra numbers we add an extra cup!
Each cup we add doubles the number of values we can store
№13 слайд
Содержание слайда: We don’t need the cups now.
We don’t need the cups now.
Let’s understand how this works
We shall look for repetitive patterns and see what they mean
№14 слайд
№15 слайд
Содержание слайда: Convert from Binary to Decimal
When we translate from the binary base (base 2) the decimal base (base 10 – ten fingers)
The first binary digit tells us whether to add 1
The second binary digit tells us whether to add 2
The third binary digit tells us whether to add 4
The fourth binary digit tells us whether to add ??
№16 слайд
Содержание слайда: Convert from Binary to Decimal
When we translate from the binary base to the decimal base
The first binary digit tells us whether to add 1
Every digit afterwards tells us whether to add exactly two times as much a the previous digit
Lets try this out
№17 слайд
Содержание слайда: The binary system (computer)
The way the computer stores numbers
Base 2
Digits 0 and 1
Example:
110110112
msd lsd
(most significant digit) (least significant digit)
№18 слайд
Содержание слайда: The decimal system (ours)
Probably because we started counting with our fingers
Base 10
Digits 0,1,2,3,4,5,6,7,8,9
Example:
7641321910
msd lsd
№19 слайд
Содержание слайда: Significant Figures
Significant Figures:
Important in science for precision of measurements.
All non-zero digits are significant
Leading zeros are not significant
e.g. = 3.14 (to 3 s.f.) = 3.142 (to 4 s.f.) = 3.1416 (to 5 s.f.)
№20 слайд
Содержание слайда: Some binary numbers!!!
№21 слайд
Содержание слайда: Convert from Binary to Decimal
Lets make this more mathematical,
We now use powers of 2 to represent 1,2,4,8,…
Note that the power is the index of the digit, when the indices start from 0 (first index is 0)
(digit with index 6 corresponds to 26)
№22 слайд
Содержание слайда: Convert from Binary to Decimal
Example of how to use what we learned to convert from binary to decimal
№23 слайд
Содержание слайда: Idea for Converting Decimal to Binary
Digit at position 0 is easy.
It is 1 if the number is even and 0 otherwise
Why?
In a binary number only the least significant digit (20=1)
№24 слайд
Содержание слайда: Convert from Decimal to Binary
№25 слайд
Содержание слайда: What Happens when we Convert from Decimal to Binary
№26 слайд
Содержание слайда: Decimal to Binary conversion Algorithmically:
Natural Numbers
1. Input n (natural no.)
2. Repeat
2.1. Output n mod 2
2.2. n n div 2
until n = 0
№27 слайд
Содержание слайда: Convert from Decimal to Binary
№28 слайд
Содержание слайда: Numbers we can already represent
Natural numbers: 1, 2, 3, 4, …
Alternative versions of the number six
Decimal: 6
Alphabetically: six
Roman: VI
Tallying:
№29 слайд
Содержание слайда: What’s still missing
Fractional numbers (real numbers)
Versions of one and a quarter
Mixed number: 1¼,
Improper fraction: 5/4,
Decimal: 1.25
№30 слайд
Содержание слайда: Decimal numbers (base 10)
String of digits
- symbol for negative numbers
Decimal point
A positional number system, with the index giving the ‘value’ of each position.
Example:
3583.102 = 3 x 103 + 5 x 102 + 8 x 101 +
3 x 100 + 1 x 10-1 + 0 x 10-2 + 2 x 10-3
№31 слайд
Содержание слайда: Representing Decimal numbers in Binary
We can use two binary numbers to represent a fraction by letting the first number be the enumerator and the other be denominator
Problem: we want operation such as addition and subtraction to execute fast. This representation is not optimal.
№32 слайд
Содержание слайда: Representing Fractions in Binary
Use a decimal point like in decimal numbers
There are two binary numbers the first is the number before the (radix) point and the other after the point
№33 слайд
Содержание слайда: Representing decimal numbers in binary
№34 слайд
Содержание слайда: Convert fractional part from Decimal to Binary
To convert the decimal part:
№35 слайд
Содержание слайда: Negative numbers
First bit (MSB) is the sign bit
If it is 0 the number is positive
If it is 1 the number is negative
Goal when definition was chosen:
Maximize use of memory
Make computation easy
№36 слайд
Содержание слайда: Negative Numbers –
Calculate two’s Complement
The generate two’s complement
Write out the positive version of number,
Write complement of each bit
(0 becomes 1 and 1 becomes 0)
Add 1
The result is the two’s complement and the negative version of the number
№37 слайд
Содержание слайда: Negative Numbers –
Two’s Complement (examples)
3bit 8bit
011 310 00011101 2910 number
100 11100010 complement
+
001 00000001 +1
=== ========
101 -310 11100011 -2910 2’s complement
№38 слайд
Содержание слайда: Negative numbers – Two’s Complement(3 bits)
First bit (MSB) is the sign bit
If it is 0 the number is positive
If it is 1 the number is negative
Goal when definition was chosen:
Maximize use of memory
Make computation easy
№39 слайд
Содержание слайда: Negative numbers – Two’s Complement (4 bits)
№40 слайд
Содержание слайда: Computer representation
Fixed length
Integers
Real
Sign
№41 слайд
Содержание слайда: Bits, bytes, words
Bit: a single binary digit
Byte: eight bits
Word: Depends!!!
Long Word: two words
№42 слайд
Содержание слайда: Integers
A two byte integer
16 bits
216 possibilities 65536
-32768 n 32767 or 0 n 65535
№43 слайд
Содержание слайда: Signed integers
№44 слайд
Содержание слайда: Real numbers
‘Human’ form: 4563.2835
Exponential form: 0.45632835 x 104
General form: m x be
Normalised binary exponential form: m x 2e
№45 слайд
Содержание слайда: Real numbers
Conversion from Human to Exponential and back
655.54 = 0. 65554 * 103
0.000545346 = 0. 545346 *10-3
0.523432 * 105 = 52343.2
0.7983476 * 10-4 = 0.00007983476
№46 слайд
Содержание слайда: Real numbers 2
For a 32 bit real number
Sign, 1 bit
Significand, 23 bits
Exponent, 8 bits
№47 слайд
Содержание слайда: Types of numbers
Integers: …, -3, -2, -1, 0, 1, 2, 3, …
Rational numbers: m/n, where m and n are integers and n 0.
Examples: ½, 5/3, ¼ = 0.25 1/3 = 0.3333…
Irrational numbers,
examples: 2 1.414, 22/7 3.14159
e 2.718.
№48 слайд
Содержание слайда: Other representations
Base Index form
Number = baseindex
e.g. 100 = 102
Percentage form
Percentage = number/100
e.g. 45% = 45/100 = 0.45
20% = 20/100 = 0.2
110% = 110/100 = 1.1
№49 слайд
Содержание слайда: Other number systems
Bases can be any natural number except 1.
Common examples are :
Binary (base 2)
Octal (base 8)
Hexadecimal (base 16)
We’ll show what to do with base 5 and 7 and then deal with the octal and hexadecimal bases
№50 слайд
Содержание слайда: Convert from Decimal to Base 7
№51 слайд
Содержание слайда: Convert from Base 7 to Decimal
№52 слайд
Содержание слайда: Convert from Decimal to Base 5 and back
№53 слайд
Содержание слайда: Octal
Base eight
Digits 0,1,2,3,4,5,6,7
Example: 1210 = 148 = 11002
100110111102 Binary
№54 слайд
Содержание слайда: Convert from Binary to Octal and back
№55 слайд
Содержание слайда: Hexadecimal
Base sixteen
Digits 0,1,2,3,4,5,6,7,8,9,A(10), B(11), C(12),D(13),E(14),F(15).
Example B316 = 17910 = 101100112
110101012 Binary
№56 слайд
Содержание слайда: Convert from Binary to Hexadecimal and back
№57 слайд
Содержание слайда: Writing down the hexadecimal conversion table
№58 слайд
Содержание слайда: Extra Slides
1 0 1 0 0 1 1
+1 1 1 0 1 1 1
№59 слайд
Содержание слайда: End of Lecture
№60 слайд
Содержание слайда: Extra Slides
The following slides present the same information already appearing in other slides, in a different manner.
№61 слайд
Содержание слайда: Decimal to Binary conversion 1:
Mathematical Operations
n div 2 is the quotient.
n mod 2 is the remainder.
For example:
14 div 2 = 7, 14 mod 2 = 0
17 div 2 = 8, 17 mod 2 = 1
№62 слайд
Содержание слайда: Decimal to Binary conversion 2:
Natural Numbers
1. Input n (natural no.)
2. Repeat
2.1. Output n mod 2
2.2. n n div 2
until n = 0
№63 слайд
Содержание слайда: Decimal to Binary conversion 3:
Fractional Numbers
1. Input n
2. Repeat
2.1. m 2n
2.2. Output m
2.3. n frac(m)
until n = 0
m is the integer part of m
frac(m) is the fraction part.
№64 слайд
Содержание слайда: Some hexadecimal (and binary) numbers!!!
№65 слайд