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| | #REDIRECT [[Procedural Programming Example]] | | #REDIRECT [[Procedural Programming Example]] |
| − | [[Category: Analytica User Guide]]
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| − | <breadcrumbs> Analytica User Guide > {{PAGENAME}}</breadcrumbs><br />
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| − | The following function, Factors(), computes the prime factors of an integer x. It illustrates many of the key constructs of procedural programming.
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| − | :::[[File:example1.png|400px]]
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| − | See below for an explanation of each of these constructs, and cross references to where they are.
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| − | {| class="wikitable"
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| − | ! '''Numbers identify<br />
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| − | features below'''
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| − | ! '''Function Factors(x)<br />
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| − | Definition:'''
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| − | |-
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| − | | 1
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| − | | <code>VAR result := [1];</code>
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| − | |-
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| − | | 2
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| − | | <code>VAR n := 2;</code>
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| − | |-
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| − | | 3
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| − | |<code>WHILE n <= x DO</code>
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| − | |-
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| − | | 4
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| − | |<code>BEGIN</code>
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| − | |-
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| − | | 2
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| − | | <code>VAR r := Floor(x/n);</code>
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| − | <code>IF r*n = x THEN</code>
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| − | |-
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| − | | 5
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| − | |<code>(result := Concat(result, [n]);</code>
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| − | |-
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| − | | 6
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| − | | <code>x := r)</code>
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| − | <code>ELSE n := n + 1</code>
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| − | |-
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| − | | 4,7
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| − | |<code>END; /* End While loop */</code>
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| − | |-
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| − | | 7, 8
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| − | |<code>result /* End Definition */</code>
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| − | |}
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| − | This definition illustrates these features:
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| − | # <code>VAR x := e</code> construct defines a local variable x, and sets an initial value e. See “Defining a local variable: Var v := e” on page 376 for more.
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| − | # You can group several expressions (statements) into a definition by separating them by “;” (semicolons). Expressions can be on the same line or successive lines. See “Begin-End, (), and “;” for grouping expressions” on page 376.
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| − | # <code>While test Do body</code> construct tests condition <code>Test</code>, and, if True, evaluates <code>Body</code>, and repeats until condition <code>Test</code> is False. See “While(Test) Do Body” on page 381.
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| − | # Begin <code>e1; e2; … End</code> groups several expressions separated by semicolons “;” — in this case as the body of a While loop. See “Begin-End, (), and “;” for grouping expressions” on page 376.
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| − | # <code>(e1; e2; …)</code> is another way to group expressions — in this case, as the action to be taken in the Then case. See “Begin-End, (), and “;” for grouping expressions” on page 376.
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| − | # <code>x := e</code> lets you assign the value of an expression <code>e</code> to a local variable <code>x</code> or, as in the first case, to a parameter of a function. See “Assigning to a local variable: v := e” on page 377.
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| − | # A comment is enclosed between /* and */ as an alternative to { and }.
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| − | # A group of expressions returns the value of the last expression — here the function <code>Factors</code> returns the value of <code>result</code> — whether the group is delimited by Begin and End, by parentheses marks ( and ), or, as here, by nothing.<br />
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| − | <footer>Analytica Enterprise / {{PAGENAME}} / Function List</footer>
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