RANDOM_NUMBER (The GNU Fortran Compiler) (original) (raw)

8.225 RANDOM_NUMBER — Pseudo-random number ¶

Synopsis:

CALL RANDOM_NUMBER(HARVEST)

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 has its own random number state. For details of the seeding procedure, see the documentation for the RANDOM_SEEDintrinsic.

Class:

Subroutine

Arguments:

Example:

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

Standard:

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

See also:

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