1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
|
program selection_vs_sort
use stdlib_kinds, only: int64
use stdlib_selection, only: select, arg_select
use stdlib_sorting, only: sort
implicit none
call compare_select_sort_for_median(1)
call compare_select_sort_for_median(11)
call compare_select_sort_for_median(101)
call compare_select_sort_for_median(1001)
call compare_select_sort_for_median(10001)
call compare_select_sort_for_median(100001)
contains
subroutine compare_select_sort_for_median(N)
integer, intent(in) :: N
integer :: i, k, result_arg_select, indx(N), indx_local(N)
real :: random_vals(N), local_random_vals(N)
integer, parameter :: test_reps = 100
integer(int64) :: t0, t1
real :: result_sort, result_select
integer(int64) :: time_sort, time_select, time_arg_select
logical :: select_test_passed, arg_select_test_passed
! Ensure N is odd
if (mod(N, 2) /= 1) stop
time_sort = 0
time_select = 0
time_arg_select = 0
select_test_passed = .true.
arg_select_test_passed = .true.
indx = (/(i, i=1, N)/)
k = (N + 1)/2 ! Deliberate integer division
do i = 1, test_reps
call random_number(random_vals)
! Compute the median with sorting
local_random_vals = random_vals
call system_clock(t0)
call sort(local_random_vals)
result_sort = local_random_vals(k)
call system_clock(t1)
time_sort = time_sort + (t1 - t0)
! Compute the median with selection, assuming N is odd
local_random_vals = random_vals
call system_clock(t0)
call select(local_random_vals, k, result_select)
call system_clock(t1)
time_select = time_select + (t1 - t0)
! Compute the median with arg_select, assuming N is odd
local_random_vals = random_vals
indx_local = indx
call system_clock(t0)
call arg_select(local_random_vals, indx_local, k, result_arg_select)
call system_clock(t1)
time_arg_select = time_arg_select + (t1 - t0)
if (result_select /= result_sort) select_test_passed = .FALSE.
if (local_random_vals(result_arg_select) /= result_sort) arg_select_test_passed = .FALSE.
end do
print *, "select ; N=", N, '; ', merge('PASS', 'FAIL', select_test_passed), &
'; Relative-speedup-vs-sort:', (1.0*time_sort)/(1.0*time_select)
print *, "arg_select; N=", N, '; ', merge('PASS', 'FAIL', arg_select_test_passed), &
'; Relative-speedup-vs-sort:', (1.0*time_sort)/(1.0*time_arg_select)
end subroutine
end program
|
