class template
<random>
std::linear_congruential_engine
template <class UIntType, UIntType a, UIntType c, UIntType m>class linear_congruential_engine;
Linear congruential random number engine
A pseudo-random number generator engine that produces unsigned integer numbers.
This is the simplest generator engine in the standard library. Its state is a single integer value, with the following transition algorithm:
Where x is the current state value, a and c are their respective template parameters, and m is its respective template parameter if this is greater than 0, or numerics_limits<UIntType>::max() plus 1, otherwise.
Its generation algorithm is a direct copy of the state value.
This makes it an extremely efficient generator in terms of processing and memory consumption, but producing numbers with varying degrees of serial correlation, depending on the specific parameters used.
The random numbers generated by linear_congruential_engine have a period of m.
Template parameters
- UIntType
- An unsigned integer type.
Values produced by the engine are of this type.
- a
- The multiplier parameter (a) used in the transition algorithm.
If m is not zero, this parameter should be lower than m.
- c
- The increment parameter (c) used in the transition algorithm.
If m is not zero, this parameter should be lower than m.
- m
- The modulus parameter (m) used in the transition algorithm, except if this parameter is zero.
If this parameter is zero, the value assumed for m on all operations is numerics_limits<UIntType>::max() plus one (even if UIntType cannot represent this value).
Template instantiations
- minstd_rand0
- Minimal Standard minstd_rand0 generator (class)
- minstd_rand
- Minimal Standard minstd_rand generator (class)
Member types
The following alias is a member type of list_congruential_engine:
| member type | definition | notes |
|---|
| result_type | The first template parameter (UIntType) | The type of the numbers generated. |
Member functions
- (constructor)
- Construct linear congruential engine (public member function)
- min
- Minimum value (public static member function)
- max
- Maximum value (public static member function)
- seed
- Seed engine (public member function)
- operator()
- Generate random number (public member function)
- discard
- Advance internal state (public member function)
Non-member functions
- operator<<
- Insert into output stream (function template)
- >/">operator>>
- Extract from input stream (function template)
- relational operators
- Relational operators (function template)
Member constexpr constants
| member constant | definition | notes |
|---|
| multiplier | The second template parameter (a) | The multiplier (a) used in the transition algorithm on each advance. |
| increment | The third template parameter (c) | The increment (c) used in the transition algorithm on each advance. |
| modulus | The fourth template parameter (m) | The modulus (m) used in the transition algorithm on each advance. |
| default_seed | 1u | The default seed used on construction or seeding. |