std::linear_congruential_engine

 

C++

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Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Numerics library

Common mathematical functions
Mathematical special functions (C++17)
Mathematical constants (C++20)
Basic linear algebra algorithms (C++26)
Floating-point environment (C++11)
Complex numbers
Numeric arrays
Pseudo-random number generation
Factor operations
gcd (C++17)
lcm (C++17)
Interpolations
midpoint (C++20)
lerp (C++20)
Saturation arithmetic
add_sat (C++26) sub_sat (C++26) saturate_cast (C++26)	mul_sat (C++26) div_sat (C++26)
Generic numeric operations
iota (C++11) ranges::iota (C++23) accumulate inner_product adjacent_difference partial_sum	reduce (C++17) transform_reduce (C++17) inclusive_scan (C++17) exclusive_scan (C++17) transform_inclusive_scan (C++17) transform_exclusive_scan (C++17)
Bit operations
has_single_bit (C++20)     bit_cast (C++20) bit_ceil (C++20) bit_floor (C++20) bit_width (C++20) rotl (C++20) rotr (C++20)	popcount (C++20) countl_zero (C++20) countl_one (C++20) countr_zero (C++20) countr_one (C++20) byteswap (C++23) endian (C++20)

 

Pseudo-random number generation

Uniform random bit generators
uniform_random_bit_generator (C++20)
Random number engines
linear_congruential_engine (C++11)
mersenne_twister_engine (C++11)
subtract_with_carry_engine (C++11)
Random number engine adaptors
discard_block_engine (C++11)
independent_bits_engine (C++11)
shuffle_order_engine (C++11)
Predefined random number generators
Non-deterministic random numbers
random_device (C++11)
Random number distributions
Uniform distributions
uniform_int_distribution (C++11)
uniform_real_distribution (C++11)
generate_canonical (C++11)
Bernoulli distributions
bernoulli_distribution (C++11)
binomial_distribution (C++11)
negative_binomial_distribution (C++11)
geometric_distribution (C++11)
Poisson distributions
poisson_distribution (C++11)
exponential_distribution (C++11)
gamma_distribution (C++11)
weibull_distribution (C++11)
extreme_value_distribution (C++11)
Normal distributions
normal_distribution (C++11)
lognormal_distribution (C++11)
chi_squared_distribution (C++11)
cauchy_distribution (C++11)
fisher_f_distribution (C++11)
student_t_distribution (C++11)
Sampling distributions
discrete_distribution (C++11)
piecewise_constant_distribution (C++11)
piecewise_linear_distribution (C++11)
Utilities
generate_canonical (C++11)
seed_seq (C++11)
Random number algorithms
ranges::generate_random (C++26)
C random library
rand	srand	RAND_MAX

 

std::linear_congruential_engine

Member functions

linear_congruential_engine::linear_congruential_engine (C++11)

linear_congruential_engine::seed (C++11)

Generation

linear_congruential_engine::operator() (C++11)

linear_congruential_engine::discard (C++11)

Characteristics

linear_congruential_engine::min (C++11)

linear_congruential_engine::max (C++11)

Non-member functions

operator==operator!= (C++11)(C++11)(until C++20)

operator<<operator>> (C++11)(C++11)

 

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 (LCG).

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.

Generator properties

The size of the states of linear_congruential_engine is 1, each of them consists of a single integer.

The actual modulus \(m_0\)m
0 is defined as follows:

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

The transition algorithm of linear_congruential_engine is \(TA(x_i) = (a \cdot x_i + c)\mod m_0\)TA(x
i) = (a·x
i+c) mod m
0.

The generation algorithm of linear_congruential_engine is \(GA(x_i) = (a \cdot x_i + c)\mod m_0\)GA(x
i) = (a·x
i+c) mod m
0.

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> Newer "Minimum standard", recommended by Park, Miller, and Stockmeyer in 1993

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) (C++11)	constructs the engine (public member function)
seed (C++11)	sets the current state of the engine (public member function)
Generation
operator() (C++11)	advances the engine's state and returns the generated value (public member function)
discard (C++11)	advances the engine's state by a specified amount (public member function)
Characteristics
min [static] (C++11)	gets the smallest possible value in the output range (public static member function)
max [static] (C++11)	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)