Two-column output format for a writing to .txt file - fortran

Question

This is my code:
Program Output_manipulation
Implicit none
Integer::i, j, k, i_index_1, i_index_2
Integer,parameter:: Br_sn_cvo=3, Br_nn_cv=2, Br_nn_mre=2, Le=350
Character(Le),parameter:: fmtB_1_1 = "(*(2x,i3,'.',2x,f5.2,1x,'j',1x,f5.2))"
Complex,parameter:: S_pot=cmplx((2.3,3.4))
Open(Unit=15,File='Output.txt',Status='Unknown')
Do k = 1, Br_nn_mre
i_index_1= Br_sn_cvo + Br_nn_mre + 1 + Br_nn_cv*(k-1)
i_index_2= Br_sn_cvo + Br_nn_mre + 1 + k*Br_nn_cv-1
Write(15,fmtB_1_1)i_index_1,S_pot,i_index_2,S_pot
End Do
Close(Unit=15,Status='Keep')
End Program Output_manipulation
The content of Output.txt is:
6. 2.30 j 3.40 7. 2.30 j 3.40
8. 2.30 j 3.40 9. 2.30 j 3.40
I have a intention to get this content in Outpur.txt:
6. 2.30 j 3.40 8. 2.30 j 3.40
7. 2.30 j 3.40 9. 2.30 j 3.40
I do not have a idea how to create format for this kind of writing in .txt file.
Is there some way for doing that with implied do loop?
I want from code to write column afther column.

Answer 1

This is an old-school version with implied do-loop
Program Output_manipulation
Implicit none
Integer::i,j
Open(Unit=15,File='Output.txt',Status='Unknown')
Do j=1,3
Write(15,'(3(2x,i0,2x,"Thing_",i0))') (i+j,i,i=1,3)
End Do
Close(Unit=15,Status='Keep')
End Program Output_manipulation

Answer 2

In this snippet, only a single do-loop is used. The loop index irow ranges from 0:nrows-1, where nrows is any positive integer and so can be adjusted without changing the algorithm. The initial left-hand column label min can be calculated from any variables/parameters you want, e.g. min=a+b. You can also extend the technique shown here to write more than two columns using the same logic, but you will still only need one do-loop.
!! ... types used in this snippet:
implicit none
integer :: a, b, nrows, min, irow, idx_column1, idx_colum2
complex :: spot = complx(2.3,3.4)
character(len=48) :: form
!! ... other code, assignments, etc.
form = "(*(2x,i3,'.',2x,f5.2,1x,'j',1x,f5.2))"
min = a + b
do irow = 0, nrows-1
idx_column1 = min + irow
idx_column2 = min + nrows + irow
write(*, form) idx_column1, spot, idx_column2, spot
enddo
Example output, with nrows=3:
12. 2.30 j 3.40 15. 2.30 j 3.40
13. 2.30 j 3.40 16. 2.30 j 3.40
14. 2.30 j 3.40 17. 2.30 j 3.40
If the thing you're actually printing to each line is an array of variables, you can index into it using some combination of min, nrows, irow, idx_column1, idx_column2.
Style suggestions:
Please, use whitespace between your variables like you do between words when you write a sentence. For legibility, and all that.
Try to be more succinct in your loop indexing. For example, i=Br_sn_cvo+Br_nn_mre+1+Br_nn_cv*(k-1),Br_sn_cvo+Br_nn_mre+1+k*Br_nn_cv-1 is really hard to read, or (for me) to care to read. Do it at least for us poor souls on StackOverflow.
Notes:
You don't need to trim(adjustl("My Fun Format")). Try it, you'll see.