1. Intro to Computer Programming Algorithms Lecture # 01 01/21/05
B Smith:
Required 45 to 50 minutes. Stirred up few questions. Needs to be more interactive and less general/abastract. Score 3 with improv, 2.5 if used as is.
B Smith:
Not used Fall05. Not needed; not helpful
Math 130
Intro to Computer Programming Algorithms Lecture # 01 01/21/05
B Smith:
Great for independent study; not so great otherwise.
Algorithm 1: The Morning Routine
Get out of bed
Shower
Bathe kids
Prepare cereal .

2. Overview Solving problems Algorithms Values and variables
mysterious or methodical
luck or by design
Algorithms
recipes
Values and variables
quantity and place holders

3. How do we solve problems?
Math 130 Intro to Computer Programming
4/12/2017 1:07 PM
How do we solve problems?
Largely empirical
“Doing heart surgery in this manner works”
History
“This is how Alice did it…”
Inspiration
“I don’t know how, but I solved it!”
Brute force
Trial-and-error
The scientific method
Largely empirical:
Partly inspiration
Empirical: build on what’s been learned
History: Simply copy someone else’s method
Inspiration: Luck!
Brute force:
Scientific Method: empirical and theoretical. Combines all the above.
B. Smith

4. The Problem-solving Process
Math 130 Intro to Computer Programming
B Smith:
Use math as a useful application. How about finding the roots of 2x^2+3x-4 = 0? What would be the algorithm.
4/12/2017 1:07 PM
The Problem-solving Process
"Doctor, my head hurts"
Patient has elevated pressure in anterior parietal lobe
Analysis
Problem specification
1. Sterilize cranial saw
2. Anaesthetize patient
3. Remove top of skull
4. Get the big spoon...
5. etc., etc.
Design
Algorithm
Implementation
sterilize(saw,alcohol);
raise_hammer();
lower_hammer(fast);
start(saw);
/* etc. etc. */
Pbm - We initially start with a fuzzy idea of the problem and associated issues
Spec - Putting it down on paper or communicating the problem to someone else coerces more clarity (hopefully)
Problem solving is often not linear and sequential; once we get to the end, we may decide that we need to review steps. Or even during the process of problem-solving, we may need to keep looking back at our footsteps.
Program
Compilation …
Executable (solution)
B. Smith

5. The Problem-solving Process
Math 130 Intro to Computer Programming
4/12/2017 1:07 PM
The Problem-solving Process
Analysis
Problem specification
Design
Algorithm
Implementation
At the center of all this is the “algorithm.”
Program
Compilation
Executable (solution)
B. Smith

6. Math 130 Intro to Computer Programming
4/12/2017 1:07 PM
Algorithm
A sequence of instructions specifying the steps required to accomplish some task
Named after:
Muhammad ibn Mūsā al-Khwārizmi
Circa C.E. (Common Era)
From D Knuth, TAOCP. Persian textbook author, c. 825
B. Smith

7. Math 130 Intro to Computer Programming
4/12/2017 1:07 PM
Algorithm –History
Muhammad ibn Musa al-Khwarizmi
Book on arithmetic:
Hindu numeration, decimal numbers, use of zero, method for finding square root
Latin translation (c.1120 CE): “Algoritmi de numero Indorum”
Book on algebra
“Kitāb al-jabr wa’l-muqābala”
(“Rules of restoring and equating”)
B. Smith

8. Algorithm – Working Definition
A sequence of instructions describing how to do a task
As opposed to actually executing the instructions!

9. The Problem-solving Process
Math 130 Intro to Computer Programming
4/12/2017 1:07 PM
The Problem-solving Process
"Doctor, my head hurts"
Patient has elevated pressure in anterior parietal lobe.
Analysis
Problem specification
1. Sterilize cranial saw
2. Anaesthetize patient
3. Remove top of skull
4. Get the big spoon...
5. etc., etc.
Design
Algorithm
Implementation
sterilize(saw,alcohol);
raise_hammer();
lower_hammer(fast);
start(saw);
/* etc. etc. */
Recall the algorithm shown here: This is not a group of actions, but rather a group of instructions to act
Program
Compilation
Executable (solution)
B. Smith

10. Math 130 Intro to Computer Programming
4/12/2017 1:07 PM
Algorithm -- Examples
A cooking recipe
Assembly instructions for a model car, boat, etc.
The rules of how to play a game
VCR instructions
Description of a martial arts technique
Directions for driving from A to B
A knitting pattern
A car repair manual
Note emphasis on sequence of instructions. A recipe and the final item are not the same; the recipe is simply the sequence.
B. Smith

11. Algorithm – Examples (cont)
Recipe for Almond and honey slice
Recipe for Arroz con pollo

12. Bake blind for 20 minutes, then remove weights and foil
Almond and Honey Slice
Preheat oven for 200° C
Line a 30 cm  20 cm baking tray with baking paper, and then with pastry
Bake blind for 20 minutes, then remove weights and foil
Turn oven up to 220° C.
Bring remaining ingredients to a boil, stirring.
Spread evenly over pastry.
Bake until topping is bubbling and has caramelized evenly, about 15 minutes.
Cool before cutting into fingers or squares.
1/2 quantity Shortcrust Pastry
185 g unsalted butter
100 g castor sugar
5 tablespoons honey
50 ml cream
50 ml brandy or any other liqueur or spirit
300 g flaked almonds
From: Stephanie Alexander, The Cook’s Companion, Viking/Penguin, Ringwood, Victoria, 1996, p. 349.

13. Math 130 Intro to Computer Programming
4/12/2017 1:07 PM
Almond and Honey Slice
Preheat oven for 200° C
Line a 30 cm  20 cm baking tray with baking paper, and then with pastry
Bake blind for 20 minutes, then remove weights and foil
Turn oven up to 220° C.
Bring remaining ingredients to a boil, stirring.
Spread evenly over pastry.
Bake until topping is bubbling and has caramelized evenly, about 15 minutes.
Cool before cutting into fingers or squares.
1/2 quantity Shortcrust Pastry
185 g unsalted butter
100 g castor sugar
5 tablespoons honey
50 ml cream
50 ml brandy or any other liqueur or spirit
300 g flaked almonds
Instructions are given in the order in which they are performed (“executed”)
To “bake blind” is an English term. See:
How to... Bake blind
by Terry Farris
‘Baking blind’ means cooking a pastry case without any filling. By baking the pastry before adding the contents, you're guaranteed a crisp, non-soggy pie case
How many times has your home-made quiche or tart fallen apart because of a soggy pie case? The simple way to avoid this common problem is blind baking: fully pre-bake the pastry then cook the pie or tart again with the filling in place. …
NB: Pie weights are used to give the crust its shape during the “blind baking”. the pie weights could be ceramic, metal, etc. See
From: Stephanie Alexander, The Cook’s Companion, Viking/Penguin, Ringwood, Victoria, 1996, p. 349.
B. Smith

14. Correct Algorithm?
Cut chicken into pieces and brown the pieces on all sides in a casserole dish in hot olive oil.
Remove the chicken; to the juices in the casserole add garlic, onions and green peppers, and sauté until onion is golden.
Add bay leaf, whole tomatoes, and chicken broth.
When the broth boils add salt, saffron and rice.
Arrange chicken on rice, cover casserole and bake in a moderate oven (350°F) for 20 minutes or until the rice is tender.
Add beans and artichokes during last 10 minutes of cooking.
From: “Arroz Con Pollo” in The Margaret Fulton Cookbook, Hamlyn, Sydney, 1968.

15. Correct Algorithm?
Cut chicken into pieces and brown the pieces on all sides in a casserole dish in hot olive oil.
Remove the chicken and to the juices in the casserole add garlic, onions and green peppers, and sauté until onion is golden.
Add bay leaf, whole tomatoes, and chicken broth.
When the broth boils add salt, saffron and rice.
Arrange chicken on rice, cover casserole and bake in a moderate oven (350°F) for 20 minutes or until the rice is tender.
Add beans and artichokes during last 10 minutes of cooking.
From: “Arroz Con Pollo” in The Margaret Fulton Cookbook, Hamlyn, Sydney, 1968.

16. Correct Algorithm?
Cut chicken into pieces and brown the pieces on all sides in a casserole dish in hot olive oil.
Remove the chicken and to the juices in the casserole add garlic, onions and green peppers, and sauté until onion is golden.
Add bay leaf, whole tomatoes, and chicken broth.
When the broth boils add salt, saffron and rice.
Arrange chicken on rice, cover casserole and bake in a moderate oven (350°F) for 10 minutes.
Add beans and artichokes.
Cover, and bake for another 10 minutes or until rice is tender.

17. From Algorithms to Programs
Algorithm: A sequence of instructions describing how to do a task (or process)
Problem
C Program

18. Components of an Algorithm
Variables and values
Instructions
Sequences
Procedures
Selections
Repetitions
Documentation

19. Math 130 Intro to Computer Programming
4/12/2017 1:07 PM
Values
Represent quantities, amounts, rates, etc.
May be numerical, alphabetical or even other items
A related unit may or may not be specified
Add 3 cups of flour
Pull rip-cord
Example:
Recipe ingredients (how big, how hot, how long)
Note distinction b/t values and quantities. Values are dimensions, temperatures, etc.
B. Smith

20. Bake blind for 20 minutes, then remove weights and foil
Almond and Honey Slice
Preheat oven for 200° C
Line a 30 cm  20 cm baking tray with baking paper, and then with pastry
Bake blind for 20 minutes, then remove weights and foil
Turn oven up to 220° C.
Bring remaining ingredients to a boil, stirring.
Spread evenly over pastry.
Bake until topping is bubbling and has caramelised evenly, about 15 minutes.
Cool before cutting into fingers or squares.
1/2 quantity Shortcrust Pastry
185 g unsalted butter
100 g castor sugar
5 tablespoons honey
50 ml cream
50 ml brandy or any other liqueur or spirit
300 g flaked almonds
From: Stephanie Alexander, The Cook’s Companion, Viking/Penguin, Ringwood, Victoria, 1996, p. 349.

21. Bake blind for 20 minutes, then remove weights and foil
Almond and Honey Slice
Preheat oven for 200° C
Line a 30 cm  20 cm baking tray with baking paper, and then with pastry
Bake blind for 20 minutes, then remove weights and foil
Turn oven up to 220° C.
Bring remaining ingredients to a boil, stirring.
Spread evenly over pastry.
Bake until topping is bubbling and has caramelised evenly, about 15 minutes.
Cool before cutting into fingers or squares.
1/2 quantity Shotcrust Pastry
185 g unsalted butter
100 g castor sugar
5 tablespoons honey
50 ml cream
50 ml brandy or any other liqueur or spirit
300 g flaked almonds
From: Stephanie Alexander, The Cook’s Companion, Viking/Penguin, Ringwood, Victoria, 1996, p. 349.

22. Variables Are containers for values – places to store values Example:
This jar
can contain
10 cookies
50 grams of sugar
3 slices of cake
etc.
Values
Variable

23. Restrictions on Variables
Variables may be restricted to contain a specific type of value

24. Components of an Algorithm
Values and Variables
Instruction (a.k.a. primitive)
Sequence (of instructions)
Procedure (involving instructions)
Selection (between instructions)
Repetition (of instructions)
Documentation (beside instructions)

25. Instructions (Primitives)
Some action that is simple...
...and unambiguous...
...that the system knows about...
...and should be able to actually do

26. Instructions – Examples
Math 130 Intro to Computer Programming
4/12/2017 1:07 PM
Instructions – Examples
Directions to perform specific actions on values and variables.
Take off your shoes
Count to 10
Cut along dotted line
Knit 1
Purl 2
Firmly Pull rip-cord
Sift 10 grams of sulfur
B. Smith

27. Instructions -- Application
Some instructions can only be applied to specific types of values or variables
Examples:
Chop

28. Instructions (Primitives) -- Recommendations
When writing an algorithm, make each instruction simple and unambiguous
Example:
Cut chicken into pieces.
Heat olive oil in a casserole dish.
Brown the chicken pieces in the casserole dish.
Cut chicken into pieces and brown the pieces on all sides in a casserole dish in hot olive oil.

29. Instruction (Primitives)
When writing an algorithm, make the instructions simple and unambiguous.
Example:
A “sequence” of simple instructions
Cut chicken into pieces.
Heat olive oil in a casserole dish.
Brown the chicken pieces in the casserole dish.
Cut chicken into pieces and brown the pieces on all sides in a casserole dish in hot olive oil.

30. Math 130 Intro to Computer Programming
Summary
4/12/2017 1:07 PM
Problem Solving Process
Algorithms
Components of Algorithms
Values and Variables
Instructions
to be continued...
Reading
Bronson, Ch 1 and Ch 2
B. Smith