Error handling approaches

8

(4) Consider a parameterized derived type “container” toward matrices and associated vectors, that provides a surefire and efficient method for bounds matching. Intel oneAPI IFORT is now quite functional here, so appears to be NAG Fortran 7.0.

..
type :: mat_t(n,m)  ! may be just 'n' for square matrices
   integer, len :: n, m
   real :: xmat(n,m)
   real :: yvec(n)
   integer :: iuse(n)
..
contains
   subroutine foo( this, luse )
      type(mat_t(n=*,m=*)), intent(inout) :: this
      logical, intent(in), optional :: luse
      ! No bounds checking necessary here
      if ( present(luse) ) then
         if ( luse ) then ! use this%iuse in the instructions
..