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15_matrices

15_matrices - Introduction to Computers and Programming JK...

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Introduction to Computers and Programming JK Lecture 15 Recap Prof. I. K. Lundqvist Reading: Oct 7 2003 FK pp. 557-563, handout • Defining and Manipulating 1D Arrays • Representing 2D arrays as 1D arrays • Today – Multi-Dimensional Arrays – Matrices – Operations of Matrices – The Matrix Package

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Two-dimensional Arrays • Two indices needed to reference elements in the array Amsterdam Berlin London Madrid Paris Rome Stockholm Amsterdam 0 648 494 1752 495 1735 1417 Berlin 648 0 1101 2349 1092 1588 1032 London 494 1101 0 1661 404 1870 1807 Madrid 1752 2349 1661 0 1257 2001 3138 Paris 495 1092 404 1257 0 1466 1881 Rome 1735 1588 1870 2001 1466 0 2620 Stockholm 1417 1032 1807 3138 1881 2620 0 max_dist : constant type Distances 0 .. max_dist; type City is Rome, Stockholm); type distance_table (City, City) of Distances; inter_city : distance_table := traveled : distance_table := ( others => (others => 0) ); your_travel : distance_table; is range is array ( 494, 1101, 0, 1661, 404, 1870, 1807), ( 495, 1092, 404, 1257, 0, 1466, 1881), -- various constants used in data types := 40077; -- max distance on earth -- type declarations (Amsterdam, Berlin, London, Madrid, Paris, -- distances between various European cities -- Amst, Berl, Lond, Madr, Pari, Rome, Stock (( 0, 648, 494, 1752, 495, 1735, 1417), -- Amsterdam ( 648, 0, 1101, 2349, 1092, 1588, 1032), -- Berlin -- London (1752, 2349, 1661, 0, 1257, 2001, 3138), -- Madrid -- Paris (1735, 1588, 1870, 2001, 1466, 0, 2620), -- Rome (1417, 1032, 1807, 3138, 1881, 2620, 0)); -- Stockholm -- distances I have traveled between various cities
Using 2-D Arrays variable, use both index values put(inter_city(Berlin, Rome); traveled (Stockholm, London) := 1807; for from in Amsterdam .. Stockholm loop for to in Amsterdam .. Stockholm loop PUT(inter_city(from, to), width=>6); ; NEW_LINE; ; Multi-dimensional arrays ranges Nested loops are often used to process 2D arrays end loop end loop – Matrices • To reference elements of a 2D array -- write out the table -- write one line of the table • Often have information in a tabular form – Tables of data • Use a multi-dimensional array to repr. data

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