CSCE150 Fortran Lab12

							  CSCE150
Fortran Lab12



                1
               Outline
• Modules
  example 1
• Derived Data Types
  example 2
• exercise 1
• exercise 2




                         2
              Modules
• Fortran 90 has a new type of
  subprogram called modules
• to provide the programmers with a way
  of packing commonly used functions or
  shared data into a single unit
• A module must be saved in a separate
  .f90 file.
       Syntax of a module
MODULE module_name
IMPLICIT NONE
    [Declaration of data ]
CONTAINS
    [Declaration of subroutines or functions]
END MODULE module_name
Use modules in other program
           units
• To use a particular module in a
  program unit, a USE statement must
  be included at the very beginning.
• For example:
 PROGRAM main_program
 USE my_module
 IMPLICIT NONE
 ..........
 END PROGRAM
              example 1
MODULE DegreeRadianConversion
 IMPLICIT NONE
 REAL, PARAMETER :: PI = 3.1415926

                               example1_module.f90
CONTAINS
 REAL FUNCTION DegreeToRadian(Degree)
   IMPLICIT NONE
   REAL, INTENT(IN) :: Degree
   DegreeToRadian = Degree*PI/180
 END FUNCTION DegreeToRadian

END MODULE DegreeRadianConversion
                                        example1.f90
PROGRAM lab12_example1
USE DegreeRadianConversion
IMPLICIT NONE

REAL:: degree, radian

WRITE (*,*) ‘ Please enter the degree’
READ (*,*) degree
radian = DegreeToRadian(degree)
WRITE(*,*) ‘The converted radian is‘, radian

END PROGRAM
                   compile
f90 example1_module.f90 example1.f90 –o example1
• Attention:
  The name of the module file is listed before
   the main program file.
      Derived Data Types
• Built-in (intrinsic) data types:
  INTEGER
  REAL
  LOGICAL
  CHARACTER
• User-defined (derived) data type
  is a combination of intrinsic data types
   and previously defined derived data
   types
 Define a derived data type
TYPE :: type_name
INTEGER :: component_1
CHARACTER :: component_2
 … ( other component definitions)
END TYPE type_name
     Declare variables/arrays of a
          derived data type
TYPE (type_name) :: var1, var2


OR


TYPE (type_name), DIMENTION(10) :: array1
   Initialize variables of a derived
               data type
var1 = type_name (values of components)




  Access components of a derived
            data type
Variable_name%component
e.g. var1%component_1
    var2%component_1
            example 2
• None of intrinsic unary and binary
  operators is defined for derived data
  types.
• Fortran permits defining new unary
  and binary operators for both
  intrinsic and derived data types.
  Define +, - for a derived data
                     type
MODULE types
IMPLICIT NONE                    example2_module.f90
TYPE :: my_type
 INTEGER :: x1, x2
END TYPE my_type

! Declare interface operators
INTERFACE OPERATOR (+)
  MODULE PROCEDURE addition
END INTERFACE
INTERFACE OPERATOR (-)
  MODULE PROCEDURE subtraction
END INTERFACE
! Now define the implementing functions
CONTAINS
  TYPE (my_type) FUNCTION addition (num1, num2)
  IMPLICIT NONE
  TYPE (my_type), INTENT(IN) :: num1, num2
  ! Calculate the addition
  addition%x1 = num1%x1+num2%x1
  addition%x2 = num1%x2+num2%x2
  END FUNCTION addition

 TYPE (my_type) FUNCTION subtraction (num1, num2)
 IMPLICIT NONE
 TYPE (my_type), INTENT(IN) :: num1, num2
 ! Calculate the subtration
 subtraction%x1 = num1%x1-num2%x1
 subtraction%x2 = num1%x2-num2%x2
 END FUNCTION subtraction

END MODULE types
PROGRAM lab12_example2
USE types                                                    example2.f90
IMPLICIT NONE

TYPE (my_type) :: number1, number2, sum, sub
! Get the first my_type variable from keyboard
WRITE (*,*) 'Enter x1, x2 for the first my_type variable'
READ (*,*) number1%x1, number1%x2

! Get the second my_type variable from keyboard
WRITE (*,*) 'Enter x1, x2 for the second my_type variable'
READ (*,*) number2%x1, number2%x2

! test + (addition) operator here
sum = number1 + number2
! Output result of addition
WRITE (*,102) number1, ‘+', number2, ' =', sum
102 FORMAT ('[',I4,I4,']',A,'[',I4,I4,']',A,'[',I4,I4,']')

! test - (subtraction) operator here
sub = number1 - number2
! Output result of subtraction
WRITE (*,102) number1, ‘-', number2, ' =', sub
END PROGRAM
             exercise 1
• Write a Fortran program to convert
  radian to degree using module
• The formula is
   degree = radian * 180 / 3.1415
• Refer to example 1
            exercise 2
• Write a Fortran program to define *,
  / for a derived data type
• Refer to example 2