Coordinate Row Sum - Modern Fortran Programming

Coordinate sparse storage keeps row, column, and value arrays side by side.
Program

Play the program to sum entries from a different sparse row.
                            target_row
                            target_row = 2 (default)target_row = 1target_row = 3
                        

                            coordinate_row_sum.f90
                        
Replay: real traced execution (multi-file project)

                            program coordinate_row_sum_demo
    implicit none
    integer :: rows(4)
    integer :: cols(4)
    integer :: values(4)
    integer :: target_row
    integer :: i
    integer :: count
    integer :: total

    rows = [1, 2, 2, 3]
    cols = [1, 1, 3, 2]
    values = [5, 7, 4, 6]
    target_row = 2
    count = 0
    total = 0
    do i = 1, 4
        if (rows(i) == target_row) then
            count = count + 1
            total = total + values(i)
        end if
    end do
    print '(I0, 1X, I0, 1X, I0)', target_row, count, total
end program coordinate_row_sum_demo
program coordinate_row_sum_demo
    implicit none
    integer :: rows(4)
    integer :: cols(4)
    integer :: values(4)
    integer :: target_row
    integer :: i
    integer :: count
    integer :: total

    rows = [1, 2, 2, 3]
    cols = [1, 1, 3, 2]
    values = [5, 7, 4, 6]
    target_row = 1
    count = 0
    total = 0
    do i = 1, 4
        if (rows(i) == target_row) then
            count = count + 1
            total = total + values(i)
        end if
    end do
    print '(I0, 1X, I0, 1X, I0)', target_row, count, total
end program coordinate_row_sum_demo
program coordinate_row_sum_demo
    implicit none
    integer :: rows(4)
    integer :: cols(4)
    integer :: values(4)
    integer :: target_row
    integer :: i
    integer :: count
    integer :: total

    rows = [1, 2, 2, 3]
    cols = [1, 1, 3, 2]
    values = [5, 7, 4, 6]
    target_row = 3
    count = 0
    total = 0
    do i = 1, 4
        if (rows(i) == target_row) then
            count = count + 1
            total = total + values(i)
        end if
    end do
    print '(I0, 1X, I0, 1X, I0)', target_row, count, total
end program coordinate_row_sum_demo

                        
1rows ← [1, 2, 2, 3]⋯11rows = [1, 2, 2, 3]12cols = [1, 1, 3, 2]⋯values this step[1, 2, 2, 3]rows
2cols ← [1, 1, 3, 2]⋯11rows = [1, 2, 2, 3]12cols = [1, 1, 3, 2]13values = [5, 7, 4, 6]⋯values this step[1, 1, 3, 2]cols
3values ← [5, 7, 4, 6]⋯12cols = [1, 1, 3, 2]13values = [5, 7, 4, 6]14target_row = 2⋯values this step[5, 7, 4, 6]values
4target_row ← 2⋯13values = [5, 7, 4, 6]14target_row = 215count = 0⋯values this step2target_row
5count ← 0⋯14target_row = 215count = 016total = 0⋯values this step0count
6total ← 0⋯15count = 016total = 017do i = 1, 4⋯values this step0total
7i ← 1⋯16total = 017do i = 1, 418    if (rows(i) == target_row) then⋯values this step1i
8if (rows(i) == target_row) then⋯17do i = 1, 418    if (rows(i) == target_row) then19        count = count + 1⋯values this step.false.rows(1) == target_row
9i ← 2⋯16total = 017do i = 1, 418    if (rows(i) == target_row) then⋯values this step2i
10if (rows(i) == target_row) then⋯17do i = 1, 418    if (rows(i) == target_row) then19        count = count + 1⋯values this step.true.rows(2) == target_row
11count ← 1⋯18if (rows(i) == target_row) then19    count = count + 120    total = total + values(i)⋯values this step0 → 1count
12total ← 7⋯19    count = count + 120    total = total + values(i)21end if⋯values this step0 → 7total7values(2)
13i ← 3⋯16total = 017do i = 1, 418    if (rows(i) == target_row) then⋯values this step3i
14if (rows(i) == target_row) then⋯17do i = 1, 418    if (rows(i) == target_row) then19        count = count + 1⋯values this step.true.rows(3) == target_row
15count ← 2⋯18if (rows(i) == target_row) then19    count = count + 120    total = total + values(i)⋯values this step1 → 2count
16total ← 11⋯19    count = count + 120    total = total + values(i)21end if⋯values this step7 → 11total4values(3)
17i ← 4⋯16total = 017do i = 1, 418    if (rows(i) == target_row) then⋯values this step4i
18if (rows(i) == target_row) then⋯17do i = 1, 418    if (rows(i) == target_row) then19        count = count + 1⋯values this step.false.rows(4) == target_row
19print '(I0, 1X, I0, 1X, I0)', target_row, count, total⋯22    end do23    print '(I0, 1X, I0, 1X, I0)', target_row, count, total24end program coordinate_row_sum_demooutput2 2 11values this step2target_row2count11total
1rows ← [1, 2, 2, 3]⋯11rows = [1, 2, 2, 3]12cols = [1, 1, 3, 2]⋯values this step[1, 2, 2, 3]rows
2cols ← [1, 1, 3, 2]⋯11rows = [1, 2, 2, 3]12cols = [1, 1, 3, 2]13values = [5, 7, 4, 6]⋯values this step[1, 1, 3, 2]cols
3values ← [5, 7, 4, 6]⋯12cols = [1, 1, 3, 2]13values = [5, 7, 4, 6]14target_row = 1⋯values this step[5, 7, 4, 6]values
4target_row ← 1⋯13values = [5, 7, 4, 6]14target_row = 115count = 0⋯values this step1target_row
5count ← 0⋯14target_row = 115count = 016total = 0⋯values this step0count
6total ← 0⋯15count = 016total = 017do i = 1, 4⋯values this step0total
7i ← 1⋯16total = 017do i = 1, 418    if (rows(i) == target_row) then⋯values this step1i
8if (rows(i) == target_row) then⋯17do i = 1, 418    if (rows(i) == target_row) then19        count = count + 1⋯values this step.true.rows(1) == target_row
9count ← 1⋯18if (rows(i) == target_row) then19    count = count + 120    total = total + values(i)⋯values this step0 → 1count
10total ← 5⋯19    count = count + 120    total = total + values(i)21end if⋯values this step0 → 5total5values(1)
11i ← 2⋯16total = 017do i = 1, 418    if (rows(i) == target_row) then⋯values this step2i
12if (rows(i) == target_row) then⋯17do i = 1, 418    if (rows(i) == target_row) then19        count = count + 1⋯values this step.false.rows(2) == target_row
13i ← 3⋯16total = 017do i = 1, 418    if (rows(i) == target_row) then⋯values this step3i
14if (rows(i) == target_row) then⋯17do i = 1, 418    if (rows(i) == target_row) then19        count = count + 1⋯values this step.false.rows(3) == target_row
15i ← 4⋯16total = 017do i = 1, 418    if (rows(i) == target_row) then⋯values this step4i
16if (rows(i) == target_row) then⋯17do i = 1, 418    if (rows(i) == target_row) then19        count = count + 1⋯values this step.false.rows(4) == target_row
17print '(I0, 1X, I0, 1X, I0)', target_row, count, total⋯22    end do23    print '(I0, 1X, I0, 1X, I0)', target_row, count, total24end program coordinate_row_sum_demooutput1 1 5values this step1target_row1count5total
1rows ← [1, 2, 2, 3]⋯11rows = [1, 2, 2, 3]12cols = [1, 1, 3, 2]⋯values this step[1, 2, 2, 3]rows
2cols ← [1, 1, 3, 2]⋯11rows = [1, 2, 2, 3]12cols = [1, 1, 3, 2]13values = [5, 7, 4, 6]⋯values this step[1, 1, 3, 2]cols
3values ← [5, 7, 4, 6]⋯12cols = [1, 1, 3, 2]13values = [5, 7, 4, 6]14target_row = 3⋯values this step[5, 7, 4, 6]values
4target_row ← 3⋯13values = [5, 7, 4, 6]14target_row = 315count = 0⋯values this step3target_row
5count ← 0⋯14target_row = 315count = 016total = 0⋯values this step0count
6total ← 0⋯15count = 016total = 017do i = 1, 4⋯values this step0total
7i ← 1⋯16total = 017do i = 1, 418    if (rows(i) == target_row) then⋯values this step1i
8if (rows(i) == target_row) then⋯17do i = 1, 418    if (rows(i) == target_row) then19        count = count + 1⋯values this step.false.rows(1) == target_row
9i ← 2⋯16total = 017do i = 1, 418    if (rows(i) == target_row) then⋯values this step2i
10if (rows(i) == target_row) then⋯17do i = 1, 418    if (rows(i) == target_row) then19        count = count + 1⋯values this step.false.rows(2) == target_row
11i ← 3⋯16total = 017do i = 1, 418    if (rows(i) == target_row) then⋯values this step3i
12if (rows(i) == target_row) then⋯17do i = 1, 418    if (rows(i) == target_row) then19        count = count + 1⋯values this step.false.rows(3) == target_row
13i ← 4⋯16total = 017do i = 1, 418    if (rows(i) == target_row) then⋯values this step4i
14if (rows(i) == target_row) then⋯17do i = 1, 418    if (rows(i) == target_row) then19        count = count + 1⋯values this step.true.rows(4) == target_row
15count ← 1⋯18if (rows(i) == target_row) then19    count = count + 120    total = total + values(i)⋯values this step0 → 1count
16total ← 6⋯19    count = count + 120    total = total + values(i)21end if⋯values this step0 → 6total6values(4)
17print '(I0, 1X, I0, 1X, I0)', target_row, count, total⋯22    end do23    print '(I0, 1X, I0, 1X, I0)', target_row, count, total24end program coordinate_row_sum_demooutput3 1 6values this step3target_row1count6total
coordinate arrays `rows`, `cols`, and `values` describe each stored entry.
row filter Only entries whose row matches `target_row` contribute to the summary.
sparse row total `count` and `total` describe the selected sparse row.