! 例題 9-6  ベクトルと配列の相互代入文 ［ユーザ定義代入文 ］
MODULE vector_and_array

  IMPLICIT NONE
  TYPE vector
    REAL :: x, y, z
  END TYPE vector

  INTERFACE ASSIGNMENT ( = )
    MODULE PROCEDURE vector_to_array
  END INTERFACE

  INTERFACE ASSIGNMENT ( = )
    MODULE PROCEDURE array_to_vector
  END INTERFACE

CONTAINS

  SUBROUTINE vector_to_array( a, v )

    IMPLICIT NONE
    TYPE ( vector ), INTENT ( IN ) :: v
    REAL, INTENT ( OUT ) :: a( 1 : 3 )

    a = (/ v%x, v%y, v%z /)

  END SUBROUTINE vector_to_array

  SUBROUTINE array_to_vector( v, a )

    IMPLICIT NONE
    REAL, INTENT ( IN ) :: a( 1 : 3 )
    TYPE ( vector ), INTENT ( OUT ) :: v

    v = vector( a( 1 ), a( 2 ), a( 3 ) )

  END SUBROUTINE array_to_vector

END MODULE vector_and_array
! main
PROGRAM ex9_6

  USE vector_and_array, ONLY : vector, ASSIGNMENT ( = )
  IMPLICIT NONE
  TYPE ( vector ) :: u
  REAL :: w( 1 : 3 )

  PRINT *, 'Input 3D-vector components: '
  READ *, u

  w = u       ! vector_to_array
  u = 2E0 * w ! array_to_vector
  PRINT '( 3F8.3 )', u

END PROGRAM ex9_6