The GNU Fortran Compiler: RANDOM_INIT

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### 8.223 `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