Matakuliah
Tahun
Versi
: D0524 / Algoritma dan Pemrograman Komputer
: 2005
:
Pertemuan 01
Algorithm
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Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• Menerapkan prinsip – prinsip dasar algoritma
menggunakan pseudo code dan flowchart
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Outline Materi
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•
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History of Algorithm
Algorithm Definition
Algorithm Implementation
Examples of Algorithm
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History of Algorithm
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The word algorithm comes from the name of the 9th century
Persian mathematician Abu Abdullah Muhammad bin Musa alKhwarizmi.
The word algorism originally referred only to the rules of
performing arithmetic using Arabic numerals but evolved into
algorithm by the 18th century. The word has now evolved to
include all definite procedures for solving problems or
performing tasks.
The first case of an algorithm written for a computer was Ada
Byron's notes on the analytical engine written in 1842, for
which she is considered by many to be the world's first
programmer.
The lack of mathematical rigor in the "well-defined procedure"
definition of algorithms posed some difficulties for
mathematicians and logicians of the 19th and early 20th
centuries. This problem was largely solved with the description
of the Turing machine, an abstract model of a computer
formulated by Alan Turing.
Nowadays, a formal criterion for an algorithm is that it is a
procedure that can be implemented on a completely-specified
Turing machine or one of the equivalent formalisms.
Abu Abdullah
Muhammad
bin Musa alKhwarizmi
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Algorithm Definition
• Algorithm is a finite set of well-defined
instructions for accomplishing some task
which, given an initial state, will terminate
in a corresponding recognizable end-state
• In short, algorithm is a step–by–step
procedure to solve a problem
• Computer has no intelligence of its own –
it cannot solve our mistakes!
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Algorithm Implementation
• Flowchart
– a schematic representation of a process. They are commonly
used in business/economic presentations to help the audience
visualize the content better, or to find flaws in the process
• Pseudocode
– a generic way of describing an algorithm using the conventions
of programming languages. As the name suggests, pseudocode
generally does not actually use the syntax of any particular
language; there is no systematic standard form, although any
particular writer will generally borrow the appearance of a
particular language
– depending on the writer, pseudocode may therefore vary widely
in style, from a near-exact imitation of a real programming
language at one extreme, to a description approaching formatted
prose at the other
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Algorithm Implementation Flowchart
Common Flowchart Symbols
Terminal : Start or end of a program
Computational steps or processing function of a program
Input or output operation
Decision making and branching
Connector or joining of two parts of program
Flow Line
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Algorithm Implementation Flowchart
A simple flowchart
for what to do if a
lamp doesn't work
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Algorithm Examples – Wake Up
• We use algorithms all the time. Here is a
typical algorithm for waking up in the
morning.
Wake-up algorithm:
Get out of bed
Brush teeth
Eat breakfast
Take shower
Get dressed
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Algorithm Examples –
Temperature Conversion
• The local weather centre wants a
computer program that will accept a
temperature reading in degrees
Fahrenheit as input, convert the value to
degrees in Celsius and provide both
values as output, for its hourly weather
report.
– Develop the program logic as flowchart and
pseudocode needed to solve the problem
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Algorithm Examples –
Temperature Conversion
• Flowchart :
Start
Input
degreesF
degreesC =
(degreesF-32) *
5/9
• Pseudocode:
Input degreesF
degreesC = (degreesF-32) * 5/9
Output degreesF and degreesC
Or
Convert degreesF
to degrees C
Output
degreesF
and
degrees C
End
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Algorithm Examples – Exercises
• Sales Application:
– In a company, a salesperson’s pay is determined by how
much they have sold in a month. Sales are of two types,
items sold at regular price and those at sale price. Each
person is paid a base amount of £920 plus a commission
of 6% on regular-price sales and 3% on reduced-price
sales.
– Design the algorithm (program logic) to calculate their pay.
• Average Mark:
– A student gains 45, 53, 58 marks in three tests.
– Design an algorithm to input that information and
output their average mark.
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