std::linear_congruential_engine
| Defined in header <random>
|
||
| template< class UIntType, |
(since C++11) | |
linear_congruential_engine is a random number engine based on Linear congruential generator (LCG).
Contents |
[edit] Template parameters
| UIntType | - | The result type generated by the generator. The effect is undefined if this is not one of unsigned short, unsigned int, unsigned long, or unsigned long long. |
| a | - | the multiplier term |
| c | - | the increment term |
| m | - | the modulus term |
When m is not zero, if a >= m or c >= m is true, the program is ill-formed.
[edit] Generator properties
The size of the states of linear_congruential_engine is 1, each of them consists of a single integer.
The actual modulus m0 is defined as follows:
- If m is not zero, m0 is m.
- If m is zero, m0 is the value of std::numeric_limits<result_type>::max() plus 1 (which means m0 need not be representable as
result_type).
The transition algorithm of linear_congruential_engine is TA(xi) = (a·xi+c) mod m0.
The generation algorithm of linear_congruential_engine is GA(xi) = (a·xi+c) mod m0.
The pseudo-random number generated with the current state is also the successor state.
[edit] Predefined specializations
The following specializations define the random number engine with two commonly used parameter sets:
| Defined in header
<random> | |
| Type | Definition |
minstd_rand0 (C++11)
|
std::linear_congruential_engine<std::uint_fast32_t, 16807, 0, 2147483647>Discovered in 1969 by Lewis, Goodman and Miller, adopted as "Minimal standard" in 1988 by Park and Miller |
minstd_rand (C++11)
|
std::linear_congruential_engine<std::uint_fast32_t, |
[edit] Nested types
| Type | Definition |
result_type
|
UIntType
|
[edit] Data members
| constexpr UIntType multiplier [static] |
a (public static member constant) |
| constexpr UIntType increment [static] |
c (public static member constant) |
| constexpr UIntType modulus [static] |
m (public static member constant) |
| constexpr UIntType default_seed [static] |
1u (public static member constant) |
[edit] Member functions
Construction and Seeding | |
| constructs the engine (public member function) | |
| sets the current state of the engine (public member function) | |
Generation | |
| advances the engine's state and returns the generated value (public member function) | |
| advances the engine's state by a specified amount (public member function) | |
Characteristics | |
| [static] |
gets the smallest possible value in the output range (public static member function) |
| [static] |
gets the largest possible value in the output range (public static member function) |
[edit] Non-member functions
| (C++11)(C++11)(removed in C++20) |
compares the internal states of two pseudo-random number engines (function) |
| (C++11) |
performs stream input and output on pseudo-random number engine (function template) |
[edit] Example
| This section is incomplete Reason: no example |
