Documentation Talk:Reference Section 2 - Revision history

Jholsenback: follow up

2010-12-04T13:28:01Z

follow up

Le Forgeron: Adding bitwise_* float functions

2010-12-04T09:12:27Z

Adding bitwise_* float functions

Jholsenback: follow up

2010-09-01T11:01:15Z

follow up

Froesccn at 22:42, 31 August 2010

2010-08-31T22:42:10Z

Jholsenback: started talk page (rand/seed)

2010-01-10T18:06:55Z

started talk page (rand/seed)

New page

<code>rand(I)</code> Returns the next pseudo-random number from the stream
specified by the positive integer <code>I</code>. You must call <code>
seed()</code> to initialize a random stream before calling <code>
rand()</code>. The numbers are uniformly distributed, and have values between
<code>0.0</code> and <code>1.0</code>, inclusively. The numbers generated by
separate streams are independent random variables.



<code> seed(I)</code> Initializes a new pseudo-random stream with the
initial seed value <code>A</code>. The number corresponding to this random
stream is returned. Any number of pseudo-random streams may be used as shown
in the example below:
<pre>
#declare R1 = seed(0);
#declare R2 = seed(12345);
sphere { <rand(R1), rand(R1), rand(R1)>, rand(R2) }
</pre>

Multiple random generators are very useful in situations where you use
<code>rand()</code> to place a group of objects, and then decide to use
<code>rand()</code> in another location earlier in the file to set some
colors or place another group of objects. Without separate <code>
rand()</code> streams, all of your objects would move when you added more
calls to <code>rand()</code>. This is very annoying.

@@ Line 49: / Line 49: @@
 * Adding bitwise_and, bitwise_or & bitwise_xor: syntax description (only the FLOAT_FUNCTION of the PRE is updated) & functions description (further down, in atanh and ceil). the warning apply to all 3 functions.
 --[[User:Le Forgeron|Le Forgeron]] 09:12, 4 December 2010 (UTC)
 ----
 ====Float Expressions====

← Older revision		Revision as of 09:12, 4 December 2010
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	:* done --[[User:Jholsenback\|jholsenback]] 11:01, 1 September 2010 (UTC)		:* done --[[User:Jholsenback\|jholsenback]] 11:01, 1 September 2010 (UTC)
		+	----
		+	* Adding bitwise_and, bitwise_or & bitwise_xor: syntax description (only the FLOAT_FUNCTION of the PRE is updated) & functions description (further down, in atanh and ceil). the warning apply to all 3 functions.
		+	--[[User:Le Forgeron\|Le Forgeron]] 09:12, 4 December 2010 (UTC)
		+	----
		+	====Float Expressions====
		+	<!--<indexentry "Expressions, float" "Float, expressions">--->
		+
		+	<p>Many parts of the POV-Ray language require you to specify one or more
		+	floating point numbers. A floating point number is a number with a decimal
		+	point. Floats may be specified using literals, identifiers or functions which
		+	return float values. You may also create very complex float expressions from
		+	combinations of any of these using various familiar operators.</p>
		+	<p>
		+	Where POV-Ray needs an integer value it allows you to specify a float value
		+	and it truncates it to an integer. When POV-Ray needs a logical or boolean
		+	value it interprets any non-zero float as true and zero as false. Because
		+	float comparisons are subject to rounding errors POV-Ray accepts values
		+	extremely close to zero as being false when doing boolean functions.
		+	Typically values whose absolute values are less than a preset value <em>
		+	epsilon</em> are considered false for logical expressions. The value of <em>
		+	epsilon</em> is system dependent but is generally about 1.0e-10. Two floats
		+	<em>a</em> and <em>b</em> are considered to be equal if <em>abs(a-b) <
		+	epsilon.</em></p>
		+	<p>
		+	The full syntax for float expressions is given below. Detailed explanations
		+	are given in the following sub-sections.</p>
		+	<pre>
		+	FLOAT:
		+	NUMERIC_TERM [SIGN NUMERIC_TERM]...
		+	SIGN:
		+	+ \| -
		+	NUMERIC_TERM:
		+	NUMERIC_FACTOR [MULT NUMERIC_FACTOR]...
		+	MULT:
		+	* \| /
		+	NUMERIC_FACTOR:
		+	FLOAT_LITERAL \|
		+	FLOAT_IDENTIFIER \|
		+	SIGN NUMERIC_FACTOR \|
		+	FLOAT_FUNCTION \|
		+	FLOAT_BUILT-IN_IDENT \|
		+	( FULL_EXPRESSION ) \|
		+	! NUMERIC_FACTOR
		+	VECTOR DECIMAL_POINT DOT_ITEM FLOAT_LITERAL:
		+	[DIGIT...] [DECIMAL_POINT] DIGIT... [EXP [SIGN] DIGIT...]
		+	DIGIT:
		+	0 \| 1 \| 2 \| 3 \| 4 \| 5 \| 6 \| 7 \| 8 \| 9
		+	DECIMAL_POINT:
		+	.
		+	EXP:
		+	e \| E
		+	DOT_ITEM:
		+	x \| y \| z \| t \| u \| v \| red \| blue \| green \| filter \|
		+	transmit \| gray
		+	FLOAT_FUNCTION:
		+	abs( FLOAT ) \| acos( FLOAT ) \| acosh( FLOAT ) \| asc( STRING ) \|
		+	asin( FLOAT ) \| asinh( FLOAT ) \| atan( FLOAT) \| atanh( FLOAT) \|
		+	atan2( FLOAT , FLOAT ) \| bitwise_and( FLOAT, FLOAT, ...) \|
		+	bitwise_or (FLOAT, FLOAT, ...) \| bitwise_xor ( FLOAT, FLOAT, ...) \|
		+	ceil( FLOAT ) \| cos( FLOAT ) \| cosh( FLOAT ) \| defined(IDENTIFIER ) \|
		+	degrees( FLOAT ) \| dimensions( ARRAY_IDENTIFIER ) \|
		+	dimension_size( ARRAY_IDENTIFIER , FLOAT ) \|
		+	div( FLOAT , FLOAT ) \| exp( FLOAT ) \| file_exists( STRING ) \|
		+	floor( FLOAT ) \| int( FLOAT ) \| ln(Float \| log( FLOAT ) \|
		+	max( FLOAT , FLOAT, ... ) \| min( FLOAT , FLOAT, ... ) \|
		+	mod( FLOAT , FLOAT ) \| pow( FLOAT , FLOAT ) \|
		+	radians( FLOAT ) \| rand( FLOAT ) \| seed( FLOAT ) \|
		+	select( FLOAT, FLOAT, FLOAT [,FLOAT]) \| sin( FLOAT ) \|
		+	sinh( FLOAT ) \| sqrt( FLOAT ) \| strcmp( STRING , STRING ) \|
		+	strlen( STRING ) \| tan( FLOAT ) \| tanh( FLOAT ) \|
		+	val( STRING ) \| vdot( VECTOR , VECTOR ) \| vlength( VECTOR ) \|
		+	FLOAT_BUILT-IN_IDENT:
		+	clock \| clock_delta \| clock_on \| false \| final_clock \|
		+	final_frame \| frame_number \| initial_clock \| initial_frame \|
		+	image_width \| image_height \| no \| off \| on \| pi \| true \|
		+	version \| yes \|
		+	FULL_EXPRESSION:
		+	LOGICAL_EXPRESSION [? FULL_EXPRESSION : FULL_EXPRESSION]
		+	LOGICAL_EXPRESSION:
		+	REL_TERM [LOGICAL_OPERATOR REL_TERM]...
		+	LOGICAL_OPERATOR:
		+	& \| \| (note: this means an ampersand or a
		+	vertical bar is a logical operator)
		+	REL_TERM:
		+	FLOAT [REL_OPERATOR FLOAT]...
		+	REL_OPERATOR:
		+	< \| <= \| = \| >= \| > \| !=
		+	INT:
		+	FLOAT (note: any syntax which requires a
		+	integer INT will accept a FLOAT
		+	and it will be truncated to an
		+	integer internally by POV-Ray).
		+	</pre>
		+	----
		+	<p>
		+	<!--<indexentry primary "bitwise_and">--->
		+	<code> bitwise_and(A,B,...)</code> Bitwise And of two or more float values considered as integers.</p>
		+	<p>
		+	<!--<indexentry primary "bitwise_or">--->
		+	<code> bitwise_or(A,B,...)</code> Bitwise Or of two or more float values considered as integers.</p>
		+	<p>
		+	<!--<indexentry primary "bitwise_xor">--->
		+	<code> bitwise_xor(A,B,...)</code> Bitwise Xor of two or more float values considered as integers.</p>
		+	<p class="Warning"><strong>Note:</strong> Each parameter is first converted to integer (so fractional part is ignored), and the computation is performed on a classical int (do not expect to much precision, as convertion from a double precision number (usually with 52 bits mantissa) to an integer and back to a double precision number is not the best way to keep track of every bits).</p>

← Older revision		Revision as of 11:01, 1 September 2010
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	Considering that #macro is different from a function and clicking on the function		Considering that #macro is different from a function and clicking on the function
	keyword in the overview bring you here.[[User:Froesccn\|Froesccn]] 22:42, 31 August 2010 (UTC)		keyword in the overview bring you here.[[User:Froesccn\|Froesccn]] 22:42, 31 August 2010 (UTC)
		+
		+	:* done --[[User:Jholsenback\|jholsenback]] 11:01, 1 September 2010 (UTC)

← Older revision		Revision as of 22:42, 31 August 2010
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	calls to <code>rand()</code>. This is very annoying.</p>		calls to <code>rand()</code>. This is very annoying.</p>
	<p>		<p>
		+
		+
		+
		+
		+	I think the text <br/>
		+
		+	In addition to the above built-in functions, you may also define your own functions
		+	using the #macro directive. See the section "User Defined Macros" for more details.<br/>
		+
		+	should be changed to<br/>
		+
		+	In addition to the above built-in functions, you may also define your own functions
		+	using the function keyword. See the section "User Defined Functions" for more details.<br>
		+
		+	Considering that #macro is different from a function and clicking on the function
		+	keyword in the overview bring you here.[[User:Froesccn\|Froesccn]] 22:42, 31 August 2010 (UTC)