Difference between revisions of "Procedural Programming Example"

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<breadcrumbs> Analytica User Guide > Procedural Programming > {{PAGENAME}}</breadcrumbs><br />
 
<breadcrumbs> Analytica User Guide > Procedural Programming > {{PAGENAME}}</breadcrumbs><br />
  
This function, <code>Factors(x)</code>, computes the prime factors of an integer «x». It illustrates many of Analytica's key constructs for procedural programming:
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This function illustrates many of Analytica's key constructs for procedural programming. It computes the prime factors of an integer «x»:
  
 
:[[File:example1.png|400px]]
 
:[[File:example1.png|400px]]
  
This function definition illustrates these features:
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Here's more detail on the numbered procedural features in this function:
  
# <code>VAR x := e</code> defines a local identifier <code>x</code> that refers to the value obtained by evaluating <code>e</code>. See [[Local_Values#Defining_a_local_value|Defining a Local Value]].
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# <code>VAR x := e</code> defines a local identifier <code>x</code> and sets its value to the result of evaluating expression <code>e</code>. See [[Local_Values#Defining_a_local_value|Defining a Local Value]].
# You can group several expressions (statements) into a definition by separating them using “;” (semicolons). Expressions can be on the same line or successive lines. See [[Begin-End for Grouping Expressions]].
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# Expressions (statements) in a sequence should be separated by “;” (semicolons). The expressions can be on the same line, successive lines, or may be broken over multiple lines. Newlines are just for clarity and have no effect on the syntax. See [[Begin-End for Grouping Expressions]].
# <code>While test Do body</code> tests condition <code>Test</code>, and, if True, evaluates <code>Body</code>, and repeats until condition <code>Test</code> is False. See [[For_and_While_Loops#While.28Test.29_Do_Body|While(Test) Do Body]].
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# WHILE <code>test DO body</code> tests condition <code>est</code>, and, if True, evaluates <code>Body</code>, and repeats until <code>Test</code> is False. See [[For_and_While_Loops#While.28Test.29_Do_Body|While(Test) Do Body]].
# <code>BEGIN e1; e2; … END</code>groups a sequence of expressions separated by semicolons “;” — in this case as the body of a While loop. See  [[Begin-End for Grouping Expressions]].
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# One way to group a sequence of expressions separated by semicolons “;”  is to enclose them as <code>BEGIN e1; e2; … END</code>— in this case as the body of a While loop. See  [[Begin-End for Grouping Expressions]].
#  <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 for Grouping Expressions]].
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Another way to group a sequence of expressions is to enclose them between parentheses<code>(e1; e2; …)</code> — in this case, as the action to be taken in the Then case. See [[Begin-End for Grouping Expressions]].
 
#  <code>x := e</code> assigns the value of expression <code>e</code> to a local value <code>x</code> or, as in the first case, to a parameter of a function. See [[Local_Values#Assigning_to_a_local_value|Assigning to a local value]].
 
#  <code>x := e</code> assigns the value of expression <code>e</code> to a local value <code>x</code> or, as in the first case, to a parameter of a function. See [[Local_Values#Assigning_to_a_local_value|Assigning to a local value]].
#  The value returned from a group of expressions is the value of the last expression — here the function <code>Factors</code> returns the local value <code>result</code> — whether the group is between <code>Begin</code> and <code>End</code>, parentheses <code>(</code> and <code>)</code>, or, as here, not enclosed by anything.
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#  The value returned from a sequence of expressions, in this case the Definition of the Function, is the value of the last expression. Here the function <code>Factors</code> returns the final expression, which is simple the local value <code>result</code>.
  
 
==See Also==
 
==See Also==

Latest revision as of 01:21, 16 August 2017


This function illustrates many of Analytica's key constructs for procedural programming. It computes the prime factors of an integer «x»:

Example1.png

Here's more detail on the numbered procedural features in this function:

  1. VAR x := e defines a local identifier x and sets its value to the result of evaluating expression e. See Defining a Local Value.
  2. Expressions (statements) in a sequence should be separated by “;” (semicolons). The expressions can be on the same line, successive lines, or may be broken over multiple lines. Newlines are just for clarity and have no effect on the syntax. See Begin-End for Grouping Expressions.
  3. WHILE test DO body tests condition est, and, if True, evaluates Body, and repeats until Test is False. See While(Test) Do Body.
  4. One way to group a sequence of expressions separated by semicolons “;” is to enclose them as BEGIN e1; e2; … END— in this case as the body of a While loop. See Begin-End for Grouping Expressions.
  5. Another way to group a sequence of expressions is to enclose them between parentheses(e1; e2; …) — in this case, as the action to be taken in the Then case. See Begin-End for Grouping Expressions.
  6. x := e assigns the value of expression e to a local value x or, as in the first case, to a parameter of a function. See Assigning to a local value.
  7. The value returned from a sequence of expressions, in this case the Definition of the Function, is the value of the last expression. Here the function Factors returns the final expression, which is simple the local value result.

See Also


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