Difference between revisions of "Procedural Programming Example"

Latest revision as of 01:21, 16 August 2017

Analytica User GuideProcedural ProgrammingProcedural Programming Example

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

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

VAR x := e defines a local identifier x and sets its value to the result of evaluating expression e. See Defining a Local Value.
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.
WHILE test DO body tests condition est, and, if True, evaluates Body, and repeats until Test is False. See While(Test) Do Body.
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.
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.
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.
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.

@@ Line 2: / Line 2: @@
 <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:
+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]]
-This table identifies key constructs from the function definition above, with a number
+Here's more detail on the numbered procedural features in this function:
-:{| class="wikitable"
+# <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]].
-! '''Numbers identify<br />features below'''<nowiki/>'''
+# 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]].
-! '''Function Factors(x)<br />Definition:'''<nowiki/>'''
+# 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]].
-|-
+# 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]].
-| 1
+#  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>VAR result := [1];</code>
+#  <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 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>.
-| 2
-| <code>VAR n := 2;</code>
-|-
-| 3
-|<code>WHILE n <= x DO</code>
-|-
-| 4
-|<code>BEGIN</code>
-|-
-| 2
-|
-:<code>VAR r := Floor(x/n);</code>
-:<code>IF r*n = x THEN</code>
-|-
-| 5
-|
-::<code>(result := Concat(result, [n]);</code><code>x := r)</code>
-|-
-| 6
-|
-:<code>ELSE n := n + 1</code>
-|-
-| 4, 7
-|<code>END; </code>
-|-
-| 7, 8
-|<code>result /* End Definition */</code>
-|}
-This definition illustrates these features:
-# <code>VAR x := e</code> defines a local variable <code>x</code>, and sets its initial value to <code>e</code>. See [[Local_Variables#Defining_a_local_variable|Defining a Local Variable]].
-# 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]].
-# <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]].
-# <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]].
-#  <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]].
-#  <code>x := e</code> assigns the value of expression <code>e</code> to a local variable <code>x</code> or, as in the first case, to a parameter of a function. See [[Local_Variables#Assigning_to_a_local_variable|Assigning to a local variable]].
-#  You can add a comment (text that Analytica ignores) between <code>{</code> and <code>}</code> or between <code>/*</code> and <code>*/</code>.
-#  The value returned from a group of expressions is the value of the last expression — here the function <code>Factors</code> returns the value of the local variable<code>result</code> — whether the group is delimited by <code>Begin</code> and <code>End</code>, by parentheses, <code>(</code> and <code>)</code>, or, as here, by nothing.
 ==See Also==
-* [[Local_Variables#Defining_a_local_variable|Defining a Local Variable]]
+* [[Local_Values#Defining_a_local_value|Defining a Local Value]]
-* [[Local_Variables#Assigning_to_a_local_variable|Assigning to a local variable]]
+* [[Local_Values#Assigning_to_a_local_value|Assigning to a local value]]
 * [[Begin-End for Grouping Expressions]]
 * [[For and While Loops]]