- Because Fortran 90
encodes the size and shape information
inside
an
array variable ,
a F90 function can
discover the
size and shape of the array
- Specifying an array as parameter:
Type, DIMENSION( : ) :: paramName ! One dimensional array Type, DIMENSION( : , : ) :: paramName ! Two dimensional array And so on...
- Example:
SUBROUTINE FuncWithMatrixParam( A ) IMPLICIT NONE REAL, DIMENSION( : ) :: A integer i, j DO i = 1, SIZE(A) !! # elements in A print *, A(i), END DO print * END
- Declaring a function with an array as parameter:
Recall that an interface is used to declare a function
Syntax to declare a function with an array parameter:
INTERFACE SUBROUTINE FuncWithMatrixParam( A ) REAL, DIMENSION( : ) :: A END SUBROUTINE END INTERFACE
Example Program:
SUBROUTINE FuncWithMatrixParam( A ) IMPLICIT NONE REAL, DIMENSION( : ) :: A integer i print *, "Number of elements = ", SIZE(A) print * DO i = 1, SIZE(A) print *, A(i) END DO print * END ! ============================================================ PROGRAM Main REAL, DIMENSION(3) :: A = (/ 111, 222, 333 /) integer i INTERFACE SUBROUTINE FuncWithMatrixParam( A ) REAL, DIMENSION( : ) :: A END SUBROUTINE END INTERFACE CALL FuncWithMatrixParam( A ) END
- Example Program:
(Demo above code)
- Prog file: click here
- You can use the
SIZE and SHAPE functions
to write
highly general subroutines
to manipulate arrays
- Example: 2 dimensional array
SUBROUTINE FuncWithMatrixParam( A ) IMPLICIT NONE REAL, DIMENSION( : , : ) :: A integer i, j DO i = 1, SIZE(A,1) !! # rows in A DO j = 1, SIZE(A,2) !! # columns in A print *, A(i,j) END DO print * END
Example Program:
SUBROUTINE FuncWithMatrixParam( A ) IMPLICIT NONE REAL, DIMENSION( : , : ) :: A integer i, j DO i = 1, SIZE(A,1) DO j = 1, SIZE(A,2) print *, A(i,j) END DO END DO print * END ! ============================================================ PROGRAM Main REAL, DIMENSION(2,3) :: A DATA A/ 1, 2, 3, 4, 5, 6/ integer i INTERFACE SUBROUTINE FuncWithMatrixParam( A ) REAL, DIMENSION( : , : ) :: A END SUBROUTINE END INTERFACE CALL FuncWithMatrixParam( A ) END
- Example Program:
(Demo above code)
- Prog file: click here