program find_element_in_array
implicit none
integer, parameter :: dp = selected_real_kind(2*precision(1.0))
real(dp), parameter :: PI=3.141592653589793238462643383279502884197_dp
integer :: i
integer, parameter :: num_elements = 100000000
real(dp), parameter :: target_value = 90000000._dp*PI
real(dp), dimension(:), allocatable :: array1, array2
real :: t1, t2
integer :: loc
loc=0
allocate(array1(num_elements), array2(num_elements))
! Create array
do i = 1, num_elements
array1(i) = i*PI
end do
! method 1
call cpu_time(t1)
do i = 1, num_elements
if (array1(i) == target_value) then
loc = i
exit
endif
end do
call cpu_time(t2)
write(*,'(A,E24.16,A,I10)') "Value ", target_value, " found at ", loc
write(*,*) "CPU time: ", t2-t1
! method 2
call cpu_time(t1)
forall (i=1:num_elements) array2(i) = abs(array1(i) - target_value)
loc = minloc(array2, 1)
call cpu_time(t2)
write(*,'(A,E24.16,A,I10)') "Value ", target_value, " found at ", loc
write(*,*) "CPU time: ", t2-t1
! method 3
call cpu_time(t1)
loc = minloc(abs(array1 - target_value), 1)
call cpu_time(t2)
write(*,'(A,E24.16,A,I10)') "Value ", target_value, " found at ", loc
write(*,*) "CPU time: ", t2-t1
end program find_element_in_array
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