Advanced Programming Guide

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3.5 Modeling Objects • 111> length,> start_point,> end_point;> local mymidpoint;>> start_point := () -> pt1;> end_point := () -> pt2;> area := () -> 0;> circumference := () -> 0;> length := proc()> local x, y;> x := pt1:-xcoord() - pt2:-xcoord();> y := pt1:-ycoord() - pt2:-ycoord();> sqrt( x^2 + y^2 )> end proc;> midpoint := proc()> local x, y;> if assigned( mymidpoint ) then> mymidpoint> else> y := (pt1:-ycoord() + pt2:-ycoord())/2;> x := (pt1:-xcoord() + pt2:-xcoord())/2;> point( x, y )> end if> end proc;> end module> end proc:The segment objects implement methods in addition to the requiredarea and circumference methods. Apart from the trivial syntax methodsstart_point and end_point, there are methods for computing the lengthof a segment and its midpoint.The circle Constructor Circles are represented by using the centerand radius of the circle as instance data.> circle := proc( ctr, rad )> module()> export area, circumference, diameter,> center, centre, radius;> radius := () -> rad;> center := () -> ctr;> centre := eval( center ); # UK spelling> diameter := () -> 2 * radius();> circumference := () -> Pi * diameter();> area := () -> Pi * rad * rad;> end module> end proc:Again, the lexically scoped parameters ctr and rad encode the instancedata of the circle object.
112 • Chapter 3: <strong>Programming</strong> with ModulesNote: The remainder of the object oriented version of the Shapes packagecan be read in ShapeObj.mpl file in the samples directory of yourMaple installation.3.6 Interfaces and ImplementationsGeneric programming is a programming style and a software engineeringmethodology for software reuse. In this sense, many Maple built-in operationsare generic. The addition operator + computes sums of integers,rational numbers, complex numbers, polynomials, special functions, andso on. When using the addition operator +, it is not necessary to statehow an expression is represented. (The automatic simplifier recognizeshow Maple expressions are represented.) As with any dynamically typedlanguage, Maple allows for a great deal of generic programming. Mostbuilt-in Maple operations (including many standard library routines) arenaturally polymorphic in that they are able to perform successfully witha large variety of data formats.Generic <strong>Programming</strong> as Good Software Engineering Practice On anylarge project, it is important to write reusable code; that is, code that canperform a well-defined function in a wide variety of situations. Genericprograms do not rely on the details of how their inputs are represented.They are able to perform their function on any inputs that satisfy a specifiedset of constraints. Normally, these constraints are described in termsof the behavior of the inputs rather than on their physical representationor the storage layout of their concrete representation. This behavior issometimes called a contract. Generic programs rely only on the objectbehavior specified by the contract. They do not rely on knowledge of howan object is implemented. So, generic software separates interfaces fromimplementations.Distinction Between Local and Exported Variables The behavior specifiedby the contract for a module includes any module exports. Whateveris expressed through its local variables is private to the module, and isnot to be relied upon, or even known, by clients of the module. (Clientaccess is, in fact, the only technical difference between module locals andexports.)Before the introduction of the module system, design by contract wasenforced in Maple only by convention. Maple routines whose names hadto be enclosed in name quotes (‘) were considered private, and not for
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ii•Waterloo Maple Inc.57 Erb Stre
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Contents • v3.6 Interfaces and Im
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Contents • viiPlotting Gears . .
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Contents • ixForeign Data . . . .
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1 Introduction1.1 Purpose of This B
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2 Procedures, Variables,and Extendi
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2.1 Nested Procedures • 5procedur
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2.1 Nested Procedures • 7> A[j] :
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2.1 Nested Procedures • 9> quicks
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2.1 Nested Procedures • 11> U :=
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2.2 Procedures That Return Procedur
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2.2 Procedures That Return Procedur
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2.3 Local Variables and Invoking Pr
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assign(another_a = a);> eqn;2.3 Loc
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[ seq( s[j][c[j]], j=1..2 ) ];2.3 L
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2.3 Local Variables and Invoking Pr
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2.4 Interactive Input • 25Improve
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2.4 Interactive Input • 27> reads
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2.5 Extending Maple • 29The parse
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2.5 Extending Maple • 31> ‘type
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2.5 Extending Maple • 33The follo
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2.5 Extending Maple • 3556 IIn th
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2.5 Extending Maple • 37Extending
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2.5 Extending Maple • 39The useri
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3 Programming withModulesProcedures
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• 43> gentemp := proc()> count :=
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3.1 Syntax and Semantics3.1 Syntax
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3.1 Syntax and Semantics • 47name
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3.1 Syntax and Semantics • 49> He
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3.1 Syntax and Semantics • 51mode
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3.1 Syntax and Semantics • 53The
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3.1 Syntax and Semantics • 55true
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3.1 Syntax and Semantics • 57modu
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3.1 Syntax and Semantics • 59> m
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Buffered Files:4.2 File Types and M
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4.3 File Descriptors versus File Na
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f := fopen("testFile.txt",WRITE):>
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4.5 Input Commands • 167iostatus(
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4.5 Input Commands • 169otherwise
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4.5 Input Commands • 171y The nex
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4.5 Input Commands • 173various c
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4.5 Input Commands • 175Example T
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4.6 Output Commands • 177One-Dime
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4.6 Output Commands • 179the appr
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4.6 Output Commands • 181Writing
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4.6 Output Commands • 183z format
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4.6 Output Commands • 185• If n
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4.6 Output Commands • 187> writed
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4.7 Conversion Commands • 189Conv
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4.8 Notes to C Programmers • 191(
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5 Numerical Programmingin MapleFloa
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5.1 The Basics of evalf • 1953.14
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5.2 Hardware Floating-Point Numbers
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iterate(f, df, x0, N);> end proc:Us
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5.3 Floating-Point Models in Maple
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5.3 Floating-Point Models in Maple
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5.4 Extending the evalf Command •
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5.4 Extending the evalf Command •
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5.5 Using the Matlab Package • 21
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6 Programming with MapleGraphicsMap
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6.1 Basic Plot Functions • 217If
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6.2 Programming with Plotting Libra
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6.3 Maple Plotting Data Structures
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PLOT( CURVES( points ) );6.3 Maple
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6.4 Programming with Plot Data Stru
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6.5 Programming with the plottools
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6.6 Vector Field Plots • 257Examp
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6.6 Vector Field Plots • 259> end
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6.6 Vector Field Plots • 261input
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6.6 Vector Field Plots • 263> mak
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6.6 Vector Field Plots • 265> vec
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6.7 Generating Grids of Points •
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A := array(1..2, 1..2):> evalgrid(
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6.8 Animation • 271The gridpoints
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6.8 Animation • 2731.00.500. 0. 2
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6.8 Animation • 275> partsum := p
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6.8 Animation • 277Demonstrating
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plot3d( p, -3..3, -3..3, color=q );
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6.9 Programming with Color • 2811
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6.9 Programming with Color • 283>
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6.9 Programming with Color • 2851
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chessplot3d( sin(x)*sin(y), x=-Pi..
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7 Advanced ConnectivityIn This Chap
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7.1 Code Generation • 291Many opt
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7.2 Using Compiled Code in Maple
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char * concat( char* a, char *b ){c
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myAdd = to_maple_integer( kv, r )EN
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to_maple_char( kv, c )to_maple_comp
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7.3 System Integrity • 337by anot
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Table 7.3 Wrapper Compound TypesMap
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AInternal Representationand Manipul
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A.1 Internal Organization • 343wi
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A.2 Internal Representations of Dat
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Type Specification or TestA.2 Inter
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Length: 3 or moreA.2 Internal Repre
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A.3 The Use of Hashing in Maple •
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Index%, 174&, 31accuracy, 193, 195,
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Index • 375SAVE, 362SERIES, 363SE
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Index • 377defining numeric, 210n
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Index • 379name, 357name table, 3
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Index • 381statements, 174strings
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