Dear all,

I notice from below thread,

That using MKL may speed up the computation, so I tried MKL’s `vdsin`

function and using the same example as in the above thread,

```
!include "_rms.fi"
program avx
implicit none
!include "mkl_vml.f90"
integer, parameter :: dp = kind(0.d0)
real(dp) :: t1, t2, r
call cpu_time(t1)
r = f(100000000)
call cpu_time(t2)
print *, "Time", t2-t1
print *, r
contains
real(dp) function f(N) result(r)
integer, intent(in) :: N
integer :: i
real(dp) :: j(N)
!r = 0.0_dp
!j = 1.0_dp
!do while (j<=N)
! r = r + sin(j)
! j = j + 1.0_dp
!enddo
!j = [(i, i = 1, N)]
!r = sum( sin( dble( (/(i, i = 1,N)/) ) ) )
call vdsin(N,(dble([(i,i=1,N)])),j)
r = sum(j)
!r = sum(sin(dble([(i,i=1,N)])))
!do i = 1, N
! r = r + sin(dble(i))
!end do
return
end function
end program
```

However, before using MKL it costs 0.6s, after using MKL it cost 1.3 second. My CPU is Xeon 2186M.

So I am confused, does anyone know how to use MKL correctly?

Thank much in advance!

PS.

I am using Intel OneAPI 2020.3 on Windows, setting is -O3 -xHost, and

The original code by @certik is

```
program avx
implicit none
integer, parameter :: dp = kind(0.d0)
real(dp) :: t1, t2, r
call cpu_time(t1)
r = f(100000000)
call cpu_time(t2)
print *, "Time", t2-t1
print *, r
contains
real(dp) function f(N) result(r)
integer, intent(in) :: N
integer :: i
r = 0
do i = 1, N
r = r + sin(real(i,dp))
end do
end function
end program
```