elemental in Fortran Wiki

[[!redirects Elemental function]]
[[!redirects Elemental subroutine]]
[[!redirects Elemental procedure]]
## Elemental Procedures
Elemental functions are defined as scalar operators, with a single scalar dummy argument and a scalar return value, but they may be invoked with arrays as actual arguments in which case the function will be applied element-wise, with a conforming array return value. Such functions must also be pure functions, with no side effects, and can be indicated with the `elemental` prefix. Since it is implied that an elemental function is also pure, the `pure` prefix is not necessary.
Elemental subroutines may be defined in a similar way, however, side effects are permitted for `intent(out)` or `intent(inout)` arguments.
The main benefit of elemental procedures is that advance knowledge that a function is elemental simplifies parallel execution.
## Example
~~~~~ {: lang=fortran }
module test_mod
 implicit none
contains
 elemental real function square(x)
 real, intent(in) :: x
 square = x*x
 end function
end module
program test_prog
 use test_mod
 implicit none
 real, dimension(3) :: x = (/ 1.0, 2.0, 3.0 /)
 print *, square(x)
end program
~~~~~