Difference between revisions of "Procedural Programming Example"

Revision as of 22:30, 13 August 2017

Analytica User GuideProcedural ProgrammingProcedural Programming Example

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

This function definition illustrates these features:

VAR x := e defines a local identifier x that refers to the value obtained by evaluating e. See 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.
While test Do body tests condition Test, and, if True, evaluates Body, and repeats until condition Test is False. See While(Test) Do Body.
BEGIN e1; e2; … ENDgroups a sequence of expressions separated by semicolons “;” — in this case as the body of a While loop. See Begin-End for Grouping Expressions.
(e1; e2; …) 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.
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 group of expressions is the value of the last expression — here the function Factors returns the local value result — whether the group is between Begin and End, parentheses ( and ), or, as here, not enclosed by anything.

@@ Line 6: / Line 6: @@
 :[[File:example1.png|400px]]
-This table identifies key constructs from the function definition above, with a number
+This function definition illustrates these features:
-:{| class="wikitable"
-! '''Numbers identify<br />features below'''<nowiki/>'''
-! '''Function Factors(x)<br />Definition:'''<nowiki/>'''
-|-
-| 1
-| <code>VAR result := [1];</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 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]].
@@ Line 52: / Line 14: @@
 #  <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 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]].
-#  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 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.
-#  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 delimited by <code>Begin</code> and <code>End</code>, by parentheses, <code>(</code> and <code>)</code>, or, as here, by nothing.
 ==See Also==