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    Chapter 2

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    Programming and SoftwareChapter 2

    Objective is how to use the computer as a toolto obtain numerical solutions to a givenengineering model. There are two ways in

    using computers:Use available software

    Or, write computer programs to extend thecapabilities of available software, such as Excel

    and Matlab.

    Engineers should not be tool limited, it isimportant that they should be able to do both!

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    Computer programs are set of instructions that direct thecomputer to perform a certain task.

    To be able to perform engineering-oriented numericalcalculations, you should be familiar with the followingprogramming topics:

    Simple information representation (constants, variables, and typedeclaration)

    Advanced information representation (data structure, arrays, andrecords)

    Mathematical formulas (assignment, priority rules, and intrinsicfunctions)

    Input/Output

    Logical representation (sequence, selection, and repetition)

    Modular programming (functions and subroutines)

    We will focus the last two topics, assuming that you havesome prior exposure to programming.

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    Structured Programming

    Structured programmingis a set of rules that

    prescribe god style habits for programmer.

    An organized, well structured code

    Easily sharable

    Easy to debug and test

    Requires shorter time to develop, test, and update

    The key idea is that any numerical algorithm can becomposed of using the three fundamental structures:

    Sequence, selection, and repetition

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    Fig. 2.1

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    Sequence. Computer

    code must be

    implemented oneinstruction at a time,

    unless you instruct

    otherwise. The

    structure can beexpressed as a

    flowchart or

    pseudocode.

    Fig.2.2

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    Selection. Splitsthe programs flowinto branches

    based on outcomeof a logicalcondition.

    Fig. 2.3

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    Repetition. A means to implement instructions repeatedly.

    Fig. 2.4

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    Fig. 2.5

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    Figure 2.6

    MEEN 221 N i l M th d

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    Modular Programming

    The computer programs can be divided intosubprograms, or modules, that can be developed andtested separately.

    Modules should be as independent and self containedas possible.

    Advantages to modular design are:

    It is easier to understand the underlying logic of

    smaller modulesThey are easier to debug and test

    Facilitate program maintenance and modification

    Allow you to maintain your own library ofmodules for later use

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    Fig. 2.7

    MEEN 221 N i l M th d

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    EXCEL

    Is a spreadsheet that allow the user to enter and performcalculations on rows and columns of data.

    When any value on the sheet is changed, entire calculation isupdated, therefore, spreadsheets are ideal for what if? sorts

    of analysis. Excel has some built in numerical capabilities including

    equation solving, curve fitting and optimization.

    It also includes VBA as a macro language that can be used toimplement numerical calculations.

    It has several visualization tools, such as graphs and threedimensional plots.

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    Fig. 2.8

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    MATLAB

    Is a flagship software which was originally

    developed as a matrix laboratory. A variety of

    numerical functions, symbolic computations,

    and visualization tools have been added to the

    matrix manipulations.

    MATLAB is closely related to programming.

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    Fig. 2.9

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    Other Languages and Libraries

    Fortran 90 (IMSL)

    C++

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    Homework #1

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    Problem 2.24

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    50( ) ( ) 9.8 ( )

    80

    v t t v t v t t

    Before the chute opens (t < 10). Eulers method can be

    implemented as

    After the chute opens (t 10). The drag coefficient is changed and

    the implementation becomes

    10( ) ( ) 9.8 ( )

    80v t t v t v t t

    Problem 2.24

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    Problem 2.24

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    z =

    Columns 1 through 15

    0 1.0000 2.0000 3.0000 4.0000 5.0000 6.0000 7.0000 8.0000 9.0000

    10.0000 11.0000 12.0000 13.0000 14.0000

    -20.0000 -7.6900 3.0813 12.5061 20.7528 27.9687 34.2826 39.8073 44.6414

    48.8712 52.5723 29.5246 20.8817 17.6406 16.4252

    Columns 16 through 21

    15.0000 16.0000 17.0000 18.0000 19.0000 20.0000

    15.9695 15.7985 15.7345 15.7104 15.7014 15.6980

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    t v

    0 -20.000

    1 -7.690

    2 3.081

    3 12.5064 20.753

    5 27.969

    6 34.283

    7 39.807

    8 44.641

    9 48.871

    10 52.572

    11 29.525

    12 20.882

    13 17.641

    14 16.425

    15 15.969

    16 15.799

    17 15.734

    18 15.710

    19 15.701

    20 15 698>>