Digital Imaging in Dentistry Applications and Challenges

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     1  1 CSE1301 Computer Programming Lecture 3: Introduction to Algorithms
     2  2 Topics Solving problems Algorithms Values and variables
     3  3 How do we solve problems? We "just do" Guesswork-and-luck Trial-and-error Experience (possibly someone else's) "Scientifically"
     4  4 0100111010110010101010101001010101010100110010101010101001011010011101010101010010010111010011110101010111110101010001101… sterilize(saw,alcohol); raise_hammer(); lower hammer(fast); start(saw); /* etc. etc. */ Patient has elevated pressure in anterior parietal lobe The Problem-solving Process Design Implementation Compilation "Doctor, my head hurts" Analysis 1. Sterilize cranial saw 2. Anaesthetize patient 3. Remove top of skull 4. Get the big spoon... 5. etc., etc.
     5  5 sterilize(saw,alcohol); raise_hammer(); lower hammer(fast); start(saw); /* etc. etc. */ The Problem-solving Process Problem specification Algorithm Program Executable (solution) Analysis Design Implementation Compilation "Doctor, my head hurts" Patient has elevated pressure in anterior parietal lobe. 1. Sterilize cranial saw 2. Anaesthetize patient 3. Remove top of skull 4. Get the big spoon... 5. etc., etc. 010011101011001010101010100101010101010011001010101010100101101001110101010101001001011101001111010101011111010101000110100001101...
     6  6 The Problem-solving Process Problem specification Algorithm Program Executable (solution) Analysis Design Implementation Compilation
     7  7 Algorithm – Dictionary Definition From: Websters Revised Unabridged Dictionary, 1913: Algorism (Al"go*rism Al"go*rithm) n. [OE. algorism, algrim, augrim, OF. algorisme, F. algorithme (cf. Sp. algoritmo, OSp. alguarismo, LL. algorismus) from the Arabic Al-Khowarezmi of Khowarezm, the modern Khiwa, surname of Abu Ja'far Mohammed ben Musa, author of a work on arithmetic early in the 9th century, which was translated into Latin, such books bearing the name algorismus.
     8  8 A sequence of instructions specifying the steps required to accomplish some task Named after: Muhammad ibn Musa al-Khwarizmi of Khowarezm (now Khiva in Uzbekistan) Algorithm
     9  9 Source: http://www.atlapedia.com/online/maps/political/Kazakh_etc.htm
     10  10 Algorithm– History Muhammad ibn Musa Al-Khwarizmi Circa 160-230 A.H. (anno Hegirae) in the year of the Hegira; of the Muslim era Circa 780-850 C.E. (Common Era)
     11  11 Algorithm –History (cont) Muhammad ibn Musa Al-Khwarizmi http://www-groups.dcs.st-andrews.ac.uk/~history/Mathematicians/Al-Khwarizmi.html 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 Hisab al-jabr w’al-muqabala
     12  12 A sequence of instructions describing how to do a task Algorithm – Working Definition [As opposed to actually executing the instructions]
     13  13 Algorithm -- Examples A cooking recipe Assembly instructions for a model 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
     14  14 Algorithm – Examples (cont) Recipe for Almond and honey slice Recipe for Arroz con pollo
     15  15 Almond and Honey Slice 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 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. From: Stephanie Alexander, The Cook’s Companion, Viking/Penguin, Ringwood, Victoria, 1996, p. 349.
     16  16 Almond and Honey Slice 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 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. From: Stephanie Alexander, The Cook’s Companion, Viking/Penguin, Ringwood, Victoria, 1996, p. 349. Instructions are given in the order in which they are performed (“executed”)
     17  17 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.
     18  18 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. Correct Algorithm?
     19  19 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. Correct Algorithm?
     20  20 From Algorithms to Programs
     21  21 Components of an Algorithm Variables and values Instructions Sequences Procedures Selections Repetitions Documentation
     22  22 Values Represent quantities, amounts or measurements May be numerical or alphabetical (or other things) Often have a unit related to their purpose Example: Recipe ingredients
     23  23 Almond and Honey Slice 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 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. From: Stephanie Alexander, The Cook’s Companion, Viking/Penguin, Ringwood, Victoria, 1996, p. 349.
     24  24 Almond and Honey Slice 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 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. From: Stephanie Alexander, The Cook’s Companion, Viking/Penguin, Ringwood, Victoria, 1996, p. 349.
     25  25 Variables Are containers for values – places to store values Example:
     26  26 Restrictions on Variables Variables may be restricted to contain a specific type of value
     27  27 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)
     28  28 Instructions (Primitives) Some action that is simple... ...and unambiguous... ...that the system knows about... ...and should be able to actually do
     29  29 Instructions – Examples Take off your shoes Count to 10 Cut along dotted line Knit 1 Purl 2 Pull rip-cord firmly Sift 10 grams of arsenic Directions to perform specific actions on values and variables.
     30  30 Instructions -- Application Some instructions can only be applied to a specific type of values or variables Examples: Chop
     31  31 Instructions (Primitives) -- Recommendations When writing an algorithm, make each instruction simple and unambiguous Example: Cut chicken into pieces and brown the pieces on all sides in a casserole dish in hot olive oil. Cut chicken into pieces. Heat olive oil in a casserole dish. Brown the chicken pieces in the casserole dish.
     32  32 Instruction (Primitives) When writing an algorithm, make the instructions simple and unambiguous. Example: Cut chicken into pieces and brown the pieces on all sides in a casserole dish in hot olive oil. Cut chicken into pieces. Heat olive oil in a casserole dish. Brown the chicken pieces in the casserole dish. A “sequence” of simple instructions
     33  33 Summary Problem Solving Process Algorithms Components of Algorithms Values and Variables Instructions to be continued... Reading Deitel & Deitel, C: How to program Chapter 3, Sections 3.1 to 3.3