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8.224 RANDOM_NUMBER — Pseudo-random number ¶

Description:

For REAL argument, returns a single pseudorandom number or an array of pseudorandom numbers from the uniform distribution over the range 0 <= x < 1.

For UNSIGNED argument returns a single pseudorandom number or an array of pseudorandom numbers in over the range of 0 <= x <= HUGE(HARVEST).

The runtime-library implements the xoshiro256** pseudorandom number generator (PRNG). This generator has a period of 2^{256} - 1, and when using multiple threads up to 2^{128} threads can each generate 2^{128} random numbers before any aliasing occurs.

Note that in a multi-threaded program (e.g. using OpenMP directives), each thread will have its own random number state. For details of the seeding procedure, see the documentation for the RANDOM_SEED intrinsic.

Standard:

Fortran 90 and later, extension for UNSIGNED (see Unsigned integers)

Class:

Subroutine

Syntax:

CALL RANDOM_NUMBER(HARVEST)

Arguments:

HARVEST

Shall be a scalar or an array of type REAL.

Example:

program test_random_number
  REAL :: r(5,5)
  CALL RANDOM_NUMBER(r)
end program

See also:

RANDOM_SEED — Initialize a pseudo-random number sequence,
RANDOM_INIT — Initialize a pseudo-random number generator