Programming Reference:RandomGenerator Class - Revision history

Mellinger: /* RandomSeed (optional) */

2012-06-29T15:38:00Z

RandomSeed (optional)

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	===RandomSeed (optional)===		===RandomSeed (optional)===
	When a nonzero RandomSeed parameter is present at initialization time, the RandomGenerator class uses it as its random seed. Otherwise, it initializes itself from the current system time.		When a nonzero RandomSeed parameter is present at initialization time, the RandomGenerator class uses it as its random seed. Otherwise, it initializes itself from the current system time.

			In recent versions of BCI2000, the Operator module provides a global RandomSeed parameter for all modules, unless the RandomSeed parameter is specified on the command line, or otherwise by a core module at startup.

	==Remarks==		==Remarks==

Mellinger at 12:48, 19 August 2008

2008-08-19T12:48:24Z

← Older revision		Revision as of 12:48, 19 August 2008
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	==Location==		==Location==
	<tt>BCI2000/src/shared/utils~~/RandomGenerator~~</tt>		<tt>BCI2000/src/shared/utils</tt>

	==Synopsis==		==Synopsis==

Mellinger: /* Remarks */

2008-08-19T12:39:42Z

Remarks

← Older revision		Revision as of 12:39, 19 August 2008
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	===int operator()(int N)===		===int operator()(int N)===
	Returns a pseudo random integer in the range from 0 to N-1. This function is a template, with the ''int'' type as a template parameter. It is provided to allow using an object of type <tt>RandomGenerator</tt> as a [http://www.sgi.com/tech/stl/functors.html functor], i.e. an object that may be used as if it were a function name. A typical application would be to specify a <tt>RandomGenerator</tt> object as a third argument to the STL's [http://www.dinkumware.com/manuals/?manual=compleat&page=algorith.html#random_shuffle <tt>std::random_shuffle()</tt>] function.		Returns a pseudo random integer in the range from 0 to N-1. This function is a template, with the ''int'' type as a template parameter. It is provided to allow using an object of type <tt>RandomGenerator</tt> as a [http://www.sgi.com/tech/stl/functors.html functor], i.e. an object that may be used as if it were a function name. A typical application would be to specify a <tt>RandomGenerator</tt> object as a third argument to the STL's [http://www.dinkumware.com/manuals/?manual=compleat&page=algorith.html#random_shuffle <tt>std::random_shuffle()</tt>] function.

			==Parameters==
			===RandomSeed (optional)===
			When a nonzero RandomSeed parameter is present at initialization time, the RandomGenerator class uses it as its random seed. Otherwise, it initializes itself from the current system time.

	==Remarks==		==Remarks==

Mellinger at 14:06, 26 June 2008

2008-06-26T14:06:45Z

New page

==Location==
<tt>BCI2000/src/shared/utils/RandomGenerator</tt>

==Synopsis==
The <tt>RandomGenerator</tt> class encapsulates a pseudo random number generator.
Each class instance maintains its own internal state; for a given random seed, this ensures identical number sequences across software elements that use pseudo random numbers.

When a nonzero ''RandomSeed'' parameter is present at initialization time, the <tt>RandomGenerator</tt> class uses it as its random seed. Otherwise, it initializes itself from the current system time.

The <tt>RandomGenerator</tt> is a descendant of the [[Programming Reference:EnvironmentExtension Class|<tt>EnvironmentExtension</tt>]] class.

==Properties==
For each property, there is a getter method carrying the plain property name. Writable properties have an additional setter method prefixed with "Set".
===int Seed (rw)===
A 32-bit value representing the random number generator's internal state. On each iteration, the seed is replaced with the generator's next state.
===int RandMax (r)===
An integer constant representing the maximum number returned from the <tt>Random()</tt> method.

==Events==
===Initialize===
In the ''Initialize'' event handler, the ''Seed'' property is initialized depending on whether a ''RandomSeed'' parameter is present in the system, and on its value.
When a nonzero ''RandomSeed'' parameter is present, it is used as a random seed. Otherwise, the seed is initialized from the current system time.

==Methods==
===int Random()===
Returns a pseudo random number in the range from 0 to, and including, RandMax.
===int operator()(int N)===
Returns a pseudo random integer in the range from 0 to N-1. This function is a template, with the ''int'' type as a template parameter. It is provided to allow using an object of type <tt>RandomGenerator</tt> as a [http://www.sgi.com/tech/stl/functors.html functor], i.e. an object that may be used as if it were a function name. A typical application would be to specify a <tt>RandomGenerator</tt> object as a third argument to the STL's [http://www.dinkumware.com/manuals/?manual=compleat&page=algorith.html#random_shuffle <tt>std::random_shuffle()</tt>] function.

==Remarks==
The number sequence is generated using a standard linear congruential algorithm, with its parameters chosen as suggested in [http://www.ams.org/mcom/1999-68-225/S0025-5718-99-00996-5/S0025-5718-99-00996-5.pdf P. L'Ecuyer: A table of linear congruential generators of different sizes and good lattice structure. Mathematics of Computation, 68(225), 1999].

==See also==
[[Programming Reference:ApplicationBase Class]], [[Programming Reference:EnvironmentExtension Class]]

[[Category:Framework API]][[Category:Development]]