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9.224 RANDOM_INIT — Initialize a pseudo-random number generator

Description:
Initializes the state of the pseudorandom number generator used by RANDOM_NUMBER.
Standard:
Fortran 2018
Class:
Subroutine
Syntax:
CALL RANDOM_INIT(REPEATABLE, IMAGE_DISTINCT)
Arguments:

REPEATABLE Shall be a scalar with a LOGICAL type, and it is INTENT(IN). If it is .true., the seed is set to a processor-dependent value that is the same each time RANDOM_INIT is called from the same image. The term “same image” means a single instance of program execution. The sequence of random numbers is different for repeated execution of the program. If it is .false., the seed is set to a processor-dependent value.
IMAGE_DISTINCT Shall be a scalar with a LOGICAL type, and it is INTENT(IN). If it is .true., the seed is set to a processor-dependent value that is distinct from th seed set by a call to RANDOM_INIT in another image. If it is .false., the seed is set to a value that does depend which image called RANDOM_INIT.

Example:
          program test_random_seed
            implicit none
            real x(3), y(3)
            call random_init(.true., .true.)
            call random_number(x)
            call random_init(.true., .true.)
            call random_number(y)
            ! x and y are the same sequence
            if (any(x /= y)) call abort
          end program test_random_seed
     

See also:
RANDOM_NUMBER, RANDOM_SEED