Fortran Wiki


co_sum sums up the values of each element of a on all images of the current team. If result_image is present, the summed-up values are returned in a on the specified image only and the value of a on the other images become undefined. If result_image is not present, the value is returned on all images. If the execution was successful and stat is present, it is assigned the value zero. If the execution failed, stat gets assigned a nonzero value and, if present, errmsg gets assigned a value describing the occurred error.


TS 18508 or later


Collective subroutine


call co_sum(a [, result_image, stat, errmsg])


  • a - shall be an integer, real or complex variable, which has the same type and type parameters on all images of the team.
  • result_image - (optional) a scalar integer expression; if present, it shall have the same the same value on all images and refer to an image of the current team.
  • stat - (optional) a scalar integer variable
  • errmsg - (optional) a scalar character variable


program test
  integer :: val
  val = this_image()
  call co_sum(val, result_image=1)
  if (this_image() == 1) then
    write(*,*) "The sum is ", val ! prints (n**2 + n)/2, with n = num_images()
  end if
end program test

See also

co_max, co_min, co_reduce, co_broadcast

category: intrinsics