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Swap

This subroutine can swap two integer (scalar, vector, matrix) and two real numbers (scalar, vector, matrix). It can also swap the dimension of a Fortran array.

note

We can use this method for swapping two variables a and b, where a and b can be scalar, vector or matrix of Fortran intrinsic types.

note

We can also use this method for swaping the dimension of a multi-dimension array. For example, consider an array b(3,4), we can interchange the row and column dimension (i.e., transpose operation) by using swap.

Interface 1​

INTERFACE
  MODULE PURE SUBROUTINE Swap(a, b, i1, i2)
    REAL(Real32), ALLOCATABLE, INTENT(INOUT) :: a(:, :)
      !! the returned array
    REAL(Real32), INTENT(IN) :: b(:, :)
      !! input array, it will be untouched
    INTEGER(I4B), INTENT(IN) :: i1
      !! index 1 is Swapped with index `i1`
      !! make sure i1 is lesser than or equal to 2
    INTEGER(I4B), INTENT(IN) :: i2
      !! index 2 is Swapped with index `i2`
      !! make sure i2 is less than or equal to 2
  END SUBROUTINE Swap
END INTERFACE

Interface 2​

INTERFACE
  MODULE PURE SUBROUTINE Swap(a, b, i1, i2, i3)
    REAL(Real32|Real64), ALLOCATABLE, INTENT(INOUT) :: a(:, :, :)
    !! the returned array
    REAL(Real32|Real64), INTENT(IN) :: b(:, :, :)
    !! input array, it will be untouched
    INTEGER(I4B), INTENT(IN) :: i1
    !! index 1 is Swapped with index `i1`
    !! make sure i1 is lesser than or equal to 3
    INTEGER(I4B), INTENT(IN) :: i2
    !! index 2 is Swapped with index `i2`
    !! make sure i2 is less than or equal to 3
    INTEGER(I4B), INTENT(IN) :: i3
    !! index 3 is Swapped with index `i3`
    !! make sure i3 is less than or equal to 3
  END SUBROUTINE Swap
END INTERFACE

Interface 3​

INTERFACE
  MODULE PURE SUBROUTINE Swap(a, b, i1, i2, i3, i4)
    REAL(Real64), ALLOCATABLE, INTENT(INOUT) :: a(:, :, :, :)
    !! the returned array
    REAL(Real64), INTENT(IN) :: b(:, :, :, :)
    !! input array, it will be untouched
    INTEGER(I4B), INTENT(IN) :: i1
    !! index 1 is Swapped with index `i1`
    !! make sure i1 is lesser than or equal to 4
    INTEGER(I4B), INTENT(IN) :: i2
    !! index 2 is Swapped with index `i2`
    !! make sure i2 is less than or equal to 4
    INTEGER(I4B), INTENT(IN) :: i3
    !! index 3 is Swapped with index `i3`
    !! make sure i3 is less than or equal to 4
    INTEGER(I4B), INTENT(IN) :: i4
    !! index 4 is Swapped with index `i4`
    !! make sure i4 is less than or equal to 4
  END SUBROUTINE Swap
END INTERFACE

Interface 4​

INTERFACE
  MODULE PURE SUBROUTINE Swap(a, b)
    INTEGER(Int8| Int16 | Int32 | Int64| Real32 | Real64), INTENT(INOUT) :: a, b
  END SUBROUTINE Swap
END INTERFACE

Swap two scalar numbers.

Interface 5​

INTERFACE
  MODULE PURE SUBROUTINE Swap(a, b)
    INTEGER(Int8| Int16 | Int32 | Int64 | Real32 | Real64), INTENT(INOUT) :: a(:), b(:)
  END SUBROUTINE Swap
END INTERFACE

Interface 6​

INTERFACE
  MODULE PURE SUBROUTINE Swap(a, b)
    INTEGER(Int8| Int16 | Int32 | Int64 | Real32 | Real64), INTENT(INOUT) :: a(:,:), b(:,:)
  END SUBROUTINE Swap
END INTERFACE

Interface 7​

INTERFACE
  MODULE PURE SUBROUTINE Swap(a, b, mask)
    INTEGER(Int8| Int16 | Int32 | Int64 | Real32 | Real64), INTENT(INOUT) :: a, b
    LOGICAL(LGT), INTENT(IN) :: mask
  END SUBROUTINE Swap
END INTERFACE

Masked swap.

Interface 8​

INTERFACE
  MODULE PURE SUBROUTINE Swap(a, b, mask)
    INTEGER(Int8| Int16 | Int32 | Int64 | Real32 | Real64), INTENT(INOUT) :: a(:), b(:)
    LOGICAL(LGT), INTENT(IN) :: mask(:)
  END SUBROUTINE Swap
END INTERFACE

Interface 9​

INTERFACE
  MODULE PURE SUBROUTINE Swap(a, b, mask)
    INTEGER(Int8| Int16 | Int32 | Int64 | Real32 | Real64), INTENT(INOUT) :: a(:, :), b(:, :)
    LOGICAL(LGT), INTENT(IN) :: mask(:, :)
  END SUBROUTINE Swap
END INTERFACE