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oopfortranfortran2003derived-types

Is it possible to declare a matrix as a derived type in Fortran?

Is it possible to declare a matrix as a derived type in Fortran? For example, can something be done so that the call

class(four_by_four_matrix) :: A

call A%inv

is valid? Where inv is declared as a procedure of four_by_four_matrix?

Solution

  • The answer to the question "is it possible?" is yes, it is possible. Just put a 2d array into your type:

      type four_by_four_matrix
    real(rp) :: arr(4,4)
  contains
    procedure :: inv => four_by_four_matrix_inv
  end type

contains

  subroutine four_by_four_matrix_inv(self)
    class(four_by_four_matrix), intent(inout) :: self
    ....
    !somehow invert self%arr
  end subroutine

end module

...

type(four_by_four_matrix) :: A

call A%inv

    If you need more details, you have to make a question with your actual detailed problems.

    BTW type-bound procedures and the class keyword were introduced in Fortran 2003. Notice you don't necessarily need to use class, you can also use type(four_by_four_matrix) if your variable is not polymorphic.