Range Summary - Modern Fortran Programming

A range summary tracks the smallest and largest active values before subtracting them.
Program

Play the program to summarize a longer or shorter prefix of the measurements.
                            limit_count
                            limit_count = 4 (default)limit_count = 2limit_count = 5
                        

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

                            program range_summary_demo
    implicit none
    integer :: measurements(5)
    integer :: limit_count
    integer :: i
    integer :: low
    integer :: high
    integer :: spread

    measurements = [8, 3, 9, 7, 10]
    limit_count = 4
    low = measurements(1)
    high = measurements(1)
    do i = 2, limit_count
        if (measurements(i) < low) low = measurements(i)
        if (measurements(i) > high) high = measurements(i)
    end do
    spread = high - low
    print '(I0, 1X, I0, 1X, I0, 1X, I0)', limit_count, low, high, spread
end program range_summary_demo
program range_summary_demo
    implicit none
    integer :: measurements(5)
    integer :: limit_count
    integer :: i
    integer :: low
    integer :: high
    integer :: spread

    measurements = [8, 3, 9, 7, 10]
    limit_count = 2
    low = measurements(1)
    high = measurements(1)
    do i = 2, limit_count
        if (measurements(i) < low) low = measurements(i)
        if (measurements(i) > high) high = measurements(i)
    end do
    spread = high - low
    print '(I0, 1X, I0, 1X, I0, 1X, I0)', limit_count, low, high, spread
end program range_summary_demo
program range_summary_demo
    implicit none
    integer :: measurements(5)
    integer :: limit_count
    integer :: i
    integer :: low
    integer :: high
    integer :: spread

    measurements = [8, 3, 9, 7, 10]
    limit_count = 5
    low = measurements(1)
    high = measurements(1)
    do i = 2, limit_count
        if (measurements(i) < low) low = measurements(i)
        if (measurements(i) > high) high = measurements(i)
    end do
    spread = high - low
    print '(I0, 1X, I0, 1X, I0, 1X, I0)', limit_count, low, high, spread
end program range_summary_demo

                        
1measurements ← [8, 3, 9, 7, 10]⋯10measurements = [8, 3, 9, 7, 10]11limit_count = 4⋯values this step[8, 3, 9, 7, 10]measurements
2limit_count ← 4⋯10measurements = [8, 3, 9, 7, 10]11limit_count = 412low = measurements(1)⋯values this step4limit_count
3low ← 8⋯11limit_count = 412low = measurements(1)13high = measurements(1)⋯values this step8low
4high ← 8⋯12low = measurements(1)13high = measurements(1)14do i = 2, limit_count⋯values this step8high
5i ← 2⋯13high = measurements(1)14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)⋯values this step2i
6low ← 3⋯14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)⋯values this step3low.true.measurements(2) < low
7if (measurements(i) > high) high = measurements(i)⋯15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)17end do⋯values this step.false.measurements(2) > high
8i ← 3⋯13high = measurements(1)14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)⋯values this step3i
9if (measurements(i) < low) low = measurements(i)⋯14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)⋯values this step.false.measurements(3) < low
10high ← 9⋯15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)17end do⋯values this step9high.true.measurements(3) > high
11i ← 4⋯13high = measurements(1)14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)⋯values this step4i
12if (measurements(i) < low) low = measurements(i)⋯14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)⋯values this step.false.measurements(4) < low
13if (measurements(i) > high) high = measurements(i)⋯15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)17end do⋯values this step.false.measurements(4) > high
14spread ← 6⋯17end do18spread = high - low19print '(I0, 1X, I0, 1X, I0, 1X, I0)', limit_count, low, high, spread⋯values this step6spread9high3low
15print '(I0, 1X, I0, 1X, I0, 1X, I0)', limit_count, low, high, spread⋯18    spread = high - low19    print '(I0, 1X, I0, 1X, I0, 1X, I0)', limit_count, low, high, spread20end program range_summary_demooutput4 3 9 6values this step4limit_count3low9high6spread
1measurements ← [8, 3, 9, 7, 10]⋯10measurements = [8, 3, 9, 7, 10]11limit_count = 2⋯values this step[8, 3, 9, 7, 10]measurements
2limit_count ← 2⋯10measurements = [8, 3, 9, 7, 10]11limit_count = 212low = measurements(1)⋯values this step2limit_count
3low ← 8⋯11limit_count = 212low = measurements(1)13high = measurements(1)⋯values this step8low
4high ← 8⋯12low = measurements(1)13high = measurements(1)14do i = 2, limit_count⋯values this step8high
5i ← 2⋯13high = measurements(1)14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)⋯values this step2i
6low ← 3⋯14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)⋯values this step3low.true.measurements(2) < low
7if (measurements(i) > high) high = measurements(i)⋯15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)17end do⋯values this step.false.measurements(2) > high
8spread ← 5⋯17end do18spread = high - low19print '(I0, 1X, I0, 1X, I0, 1X, I0)', limit_count, low, high, spread⋯values this step5spread8high3low
9print '(I0, 1X, I0, 1X, I0, 1X, I0)', limit_count, low, high, spread⋯18    spread = high - low19    print '(I0, 1X, I0, 1X, I0, 1X, I0)', limit_count, low, high, spread20end program range_summary_demooutput2 3 8 5values this step2limit_count3low8high5spread
1measurements ← [8, 3, 9, 7, 10]⋯10measurements = [8, 3, 9, 7, 10]11limit_count = 5⋯values this step[8, 3, 9, 7, 10]measurements
2limit_count ← 5⋯10measurements = [8, 3, 9, 7, 10]11limit_count = 512low = measurements(1)⋯values this step5limit_count
3low ← 8⋯11limit_count = 512low = measurements(1)13high = measurements(1)⋯values this step8low
4high ← 8⋯12low = measurements(1)13high = measurements(1)14do i = 2, limit_count⋯values this step8high
5i ← 2⋯13high = measurements(1)14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)⋯values this step2i
6low ← 3⋯14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)⋯values this step3low.true.measurements(2) < low
7if (measurements(i) > high) high = measurements(i)⋯15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)17end do⋯values this step.false.measurements(2) > high
8i ← 3⋯13high = measurements(1)14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)⋯values this step3i
9if (measurements(i) < low) low = measurements(i)⋯14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)⋯values this step.false.measurements(3) < low
10high ← 9⋯15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)17end do⋯values this step9high.true.measurements(3) > high
11i ← 4⋯13high = measurements(1)14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)⋯values this step4i
12if (measurements(i) < low) low = measurements(i)⋯14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)⋯values this step.false.measurements(4) < low
13if (measurements(i) > high) high = measurements(i)⋯15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)17end do⋯values this step.false.measurements(4) > high
14i ← 5⋯13high = measurements(1)14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)⋯values this step5i
15if (measurements(i) < low) low = measurements(i)⋯14do i = 2, limit_count15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)⋯values this step.false.measurements(5) < low
16high ← 10⋯15    if (measurements(i) < low) low = measurements(i)16    if (measurements(i) > high) high = measurements(i)17end do⋯values this step10high.true.measurements(5) > high
17spread ← 7⋯17end do18spread = high - low19print '(I0, 1X, I0, 1X, I0, 1X, I0)', limit_count, low, high, spread⋯values this step7spread10high3low
18print '(I0, 1X, I0, 1X, I0, 1X, I0)', limit_count, low, high, spread⋯18    spread = high - low19    print '(I0, 1X, I0, 1X, I0, 1X, I0)', limit_count, low, high, spread20end program range_summary_demooutput5 3 10 7values this step5limit_count3low10high7spread
initial extrema Both `low` and `high` start from the first active observation.
conditional update Each later value updates only the summary it beats.
spread The range width is `high - low` after the scan finishes.