Consider a namelist containing two-dimensional arrays. For example, the following program reads from a file "input.dat".
program test
use :: iso_fortran_env
implicit none
integer :: ierr, unit, i
real(kind=kind(0.0d0)), allocatable :: p(:, :)
namelist /VAR_p/ p
allocate(p(2,2))
open(newunit=unit, file='input.dat', status='old', iostat=ierr)
read(unit, nml=VAR_p, iostat=ierr)
close(unit)
do i = 1, size(p, 1)
write(output_unit, '(F4.2," ",F4.2)') p(i,1), p(i,2)
end do
end program test
One can provide the array p in "input.dat" as
! input.dat
&VAR_p
p(1,1) = 1.2
p(1,2) = 3.2
p(2,1) = 1.0
p(2,2) = 0.0
/
With this input the program runs fine. Nevertheless, I would rather prefer to provide the array p line-by-line. Something like
! input.dat
&VAR_p
p(1,:) = (1.2, 3.2)
p(2,:) = (1.30, 0.0)
/
Is there a syntax to achive that?
There is indeed a syntax to specify an array section in a namelist record. It's close to the requested form, but not quite.
In a namelist record, the item (1.30, 0.0) specifies a complex value not an array constructor (which means the generalization to (1.3, 0.0, 1.2) isn't a valid value). Instead you simply want to specify a list of values: 1.3, 0.0:
&VAR_p
p(1,:) = 1.2, 3.2
p(2,:) = 1.30, 0.0
/
There are some restrictions of note:
In this second case, if there are fewer values on the right-hand side than elements on the left, then it's as though the right-hand side were padded with null values.