Find the sum of each rows and each columns - fortran

Question

need to use SUM() and dim
the problem in the sum() algorithm does not calculate correctly, I can’t fix it, I need someone’s help
program main
use environment
implicit none
character(*), parameter :: input_file = "../data/input.txt", output_file = "output.txt"
integer :: In = 0, Out = 0, rows = 0, columns = 0!, i = 0
integer, allocatable :: A(:,:)
integer :: res_rows = 0, res_columns = 0
open (file=input_file, newunit=In)
read(In, *) rows, columns
allocate(A(rows, columns))
read (In, *) A
close (In)
res_rows = sum(A(1:columns+1,1), dim=1)
res_columns = sum(A(1:rows+1,1), dim=1)
!outout data
open (file=output_file, encoding=E_, newunit=Out, position='append')
write(*,*)"rows:",res_rows
write(*,*)"columns:",res_columns
close (Out)
end program main
input data from txt file
4 3
1 1 2
4 3 4
1 1 2
4 3 2
output data to txt file
rows: 4 11 4 9
columns: 10 8 10

Answer 1

Fortran is a column-major language. Your read(in,*) a is populating the matrix in the wrong order. Try writing out the first row of your matrix a. Your use of the sum intrinsic is also wrong. See below.
program main
implicit none
character(*), parameter :: input_file = "a.dat"
integer i, in, out, rows, columns
integer, allocatable :: a(:,:)
integer :: res_rows = 0, res_columns = 0
open(file=input_file, newunit=in, status='old')
read(in, *) rows, columns
allocate(a(rows, columns))
do i = 1, rows
read(in,*) a(i,:)
end do
close(in)
print '(A,4(1X,I0))', 'Sum of each row:', sum(a,dim=2)
do i = 1, rows
print '(3I3,A,I0)', a(i,:),' = ', sum(a(i,:))
end do
print *
print '(A,4(1X,I0))', 'Sum of each column:', sum(a,dim=1)
do i = 1, columns
print '(4I3,A,I0)', a(:,i),' = ',sum(a(:,i))
end do
end program main