std::linear_congruential_engine

Defined in header <random>
template < class UIntType,     UIntType a,     UIntType c,     UIntType m > class linear_congruential_engine;		(since C++11)

linear_congruential_engine is a random number engine based on Linear congruential generator

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

Generator properties

The size of the states of linear_congruential_engine is 1

The actual modulus \(\scriptsize m_0\)m0 is defined as follows:

• If m is not zero, \(\scriptsize m_0\) m0 is m
• If m is zero, \(\scriptsize m_0\) m0 is the value of std::numeric_limits <result_type> :: max ( ) plus 1 (which means \(\scriptsize m_0\) m0 need not be representable as result_type

The transition algorithm of linear_congruential_engine is \(\scriptsize TA(x_i) = (a \cdot x_i + c)\mod m_0\) TA(xi) = (a·xi+c) mod m0

The generation algorithm of linear_congruential_engine is \(\scriptsize GA(x_i) = (a \cdot x_i + c)\mod m_0\) GA(xi) = (a·xi+c) mod m0

The pseudo-random number generated with the current state is also the successor state.

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 48271, 0, 2147483647>

Nested types

Type	Definition
result_type	UIntType

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)

Member functions

Construction and Seeding
(constructor)	constructs the engine (public member function)
seed	sets the current state of the engine (public member function)
Generation
operator()	advances the engine's state and returns the generated value (public member function)
discard	advances the engine's state by a specified amount (public member function)
Characteristics
min [static]	gets the smallest possible value in the output range (public static member function)
max [static]	gets the largest possible value in the output range (public static member function)

Non-member functions

operator==operator!= (C++11)(C++11)(removed in C++20)	compares the internal states of two pseudo-random number engines (function)
operator<<operator>> (C++11)	performs stream input and output on pseudo-random number engine (function template)

Example

This section is incomplete Reason: no example