Reference:Numeric Expressions - Revision history

Jr: removed misleading (false) sentence.

2026-06-08T21:40:18Z

removed misleading (false) sentence.

Jr: fix item order typo.

2025-05-26T21:44:16Z

fix item order typo.

Jr: fix typo.

2025-05-08T13:32:13Z

fix typo.

Clipka: /* Built-in Variables */ canonicalize some version numbers

2021-06-09T14:34:02Z

Built-in Variables: canonicalize some version numbers

Jholsenback: technical correction

2020-02-10T18:00:53Z

technical correction

Jholsenback: version changes

2017-06-26T10:11:39Z

version changes

Jholsenback: version changes

2017-06-26T10:02:52Z

version changes

Jholsenback: added {{Change}} otation

2016-12-31T19:56:54Z

added {{Change}} otation

Clipka: Indexentries fix

2016-12-16T15:09:16Z

Indexentries fix

Jholsenback: roll back as problems was wikidocgen bug

2016-07-21T17:22:47Z

roll back as problems was wikidocgen bug

@@ Line 288: / Line 288: @@
 {{#indexentry:abs}}
-<p><code>abs(A)</code><br>Absolute value of <code>A</code>. If <code>A</code> is negative, returns <code>-A</code> otherwise returns <code>A</code>.</p>
+<p><code>abs(A)</code><br>Returns the absolute value of <code>A</code>.</p>
 {{#indexentry:acos}}

@@ Line 158: / Line 158: @@
 <td><code>+A -A !A</code></td>
-<td>unary minus, unary plus and logical <em>not</em></td>
+<td>unary plus, unary minus and logical <em>not</em></td>
 </tr>

@@ Line 401: / Line 401: @@
 {{#indexentry:select}}
-<p><code>select(A, B, C [,D])</code><br>It can be used with three or four parameters <code>Select</code> compares the first argument with zero, depending on the outcome it will return <code>B</code>, <code>C</code> or <code>D</code>. <code>A,B,C,D</code> can be floats or funtions.</p>
+<p><code>select(A, B, C [,D])</code><br>It can be used with three or four parameters <code>Select</code> compares the first argument with zero, depending on the outcome it will return <code>B</code>, <code>C</code> or <code>D</code>. <code>A,B,C,D</code> can be floats or functions.</p>
 <p>When used with three parameters, if <code>A &lt; 0</code> it will return <code>B</code>, else <code>C</code> (<code>A &gt;= 0</code>).</p>

@@ Line 671: / Line 671: @@
 <pre>
 #local Temp_Vers = version;  // Save previous value
-#version 3.5;                // Change to 3.5 mode
+#version 3.5;                // Change to v3.5 mode
 ...                          // Version 3.5 stuff goes here...
 #version Temp_Vers;          // Restore previous version
@@ Line 680: / Line 680: @@
 a warning and some macros may not work properly.</p>
-<p class="Note"><strong>Note:</strong> As of POV-Ray 3.7, the version compatibility option
+<p class="Note"><strong>Note:</strong> As of POV-Ray v3.7, the version compatibility option
-defaults to 3.62 rather than the actual software version. However, in POV-Ray 3.7.0,
+defaults to 3.62 (corresponding to v3.6.2) rather than the actual software version. However, in POV-Ray v3.7.0,
 <code>version</code> defaults to the actual software version. This is a {{Change}} in
-POV-Ray 3.8 so that <code>version</code> generally reflects the version compatibility option
+POV-Ray v3.8 so that <code>version</code> generally reflects the version compatibility option
 even in the default case, except when used inside the very first <code>#version</code>
 statement where it still defaults to the actual software version. Therefore, to identify

@@ Line 122: / Line 122: @@
 </pre>
-<p>Where <em>IDENTIFIER</em> is the name of the identifier up to 40
+<p>Where <em>IDENTIFIER</em> is valid identifier name and <em>EXPRESSION</em> is any valid expression which
-characters long and <em>EXPRESSION</em> is any valid expression which
+evaluates to a float value.</p>
-evaluates to a float value. </p>
+<p class="Note"><strong>Note:</strong> There should be a semi-colon after the expression in a float declaration. If omitted, it generates a warning and some macros may not work properly.</p>
-<p class="Note"><strong>Note:</strong> There should be a semi-colon after the
+<p>See also: <!--<linkto "Identifiers">Identifiers</linkto>--->[[Reference:Identifiers|Identifiers]] and <!--<linkto "#declare vs. #local">#declare vs. #local</linkto>--->[[Reference:Declare and Local Directives#declare vs. local|#declare vs. #local]] for additional information on identifier naming and scope.</p>
 <p>Here are some examples.</p>

@@ Line 685: / Line 685: @@
 defaults to 3.62 rather than the actual software version. However, in POV-Ray 3.7.0,
 <code>version</code> defaults to the actual software version. This is a {{Change}} in
-POV-Ray 3.7.1 so that <code>version</code> generally reflects the version compatibility option
+POV-Ray 3.8 so that <code>version</code> generally reflects the version compatibility option
 even in the default case, except when used inside the very first <code>#version</code>
 statement where it still defaults to the actual software version. Therefore, to identify
-POV-Ray version 3.7.1 or higher, you will need to start your scene file with the following
+POV-Ray version 3.8 or higher, you will need to start your scene file with the following
 construct:</p>
 <pre>
 #version version;
 </pre>

@@ Line 485: / Line 485: @@
 constants.</p>
-<p>{{New}} in version 3.7.1 the <code>[http://en.wikipedia.org/wiki/Turn_%28geometry%29#Tau_proposal tau]</code>
+<p>{{New}} in version 3.8 the <code>[http://en.wikipedia.org/wiki/Turn_%28geometry%29#Tau_proposal tau]</code>
 constant can be used as a more convenient and intuitive alternative to <code>2*pi</code>
 to express a full (360 degrees) turn in radians.</p>

@@ Line 98: / Line 98: @@
 have float values. The <em>DOT_ITEM</em> syntax is actually a vector or color operator but it returns a float value. See [[Reference:Vector Expressions#Operators|:Vector,operators|Vector Operators]] or [[Reference:Color Expressions#Color Operators|Color Operators]] for details. An <em> ARRAY_IDENTIFIER</em> is just the identifier name of a previously declared array, it does not include the <code>[]</code> braces nor the index. The syntax for <em>STRING</em> is in the section [[Reference:Strings|:strings|Strings]].</p>
 {{#indexentry:Literals, float}}
 {{#indexentry:Float, literals}}
 <p>Float literals are represented by an optional sign (&quot;+&quot; or
 &quot;-&quot;) digits, an optional decimal point and more digits. If the
@@ Line 110: / Line 110: @@
 <code> -2.0 -4 34 3.4e6 2e-5 .3 0.6</code></p>
 {{#indexentry:Identifiers, float}}
 {{#indexentry:Float, identifiers}}
 <p>Float identifiers may be declared to make scene files more readable and to
 parameterize scenes so that changing a single declaration changes many
@@ Line 143: / Line 143: @@
 for details.</p>
 {{#indexentry:Operators, float}}
 {{#indexentry:Float, operators}}
 <p><strong>Arithmetic expressions:</strong> Basic math expressions can be
 created from float literals, identifiers or functions using the following
@@ Line 271: / Line 270: @@
 subtract, then relational, then logical, then conditional.</p>
 {{#indexentry:Float, functions}}
 {{#indexentry:Functions, float}}
 <p>POV-Ray defines a variety of built-in functions for manipulating floats,
 vectors and strings. Function calls consist of a keyword which specifies the
@@ Line 450: / Line 449: @@
 <p>See section [[Reference:Function#Declaring User-Defined Vector Functions|:Vector,functions|Vector Functions]] and section [[Reference:Strings#String Functions|String Functions]] for other functions which are somewhat float-related but which return vectors and strings. In addition to the above built-in functions, you may also define your own functions using the <code>function</code> keyword. See the section [[Reference:Function#Declaring User-Defined Float Functions|User-Defined Functions]] for more details.</p>
 {{#indexentry:boolean}}
 {{#indexentry:Float, boolean}}
 {{#indexentry:Float, built-in constants}}
 <p>Constants are:</p>
 <pre>
@@ Line 505: / Line 503: @@
 </pre>
 {{#indexentry:Float, built-in variables}}
 <p>There are several built-in float variables. You can use them to specify
 values or to create expressions but you cannot re-declare them to change