I am experiencing a problem with a simple multithread program and
WindowsXP.

The program is as follows. It doesn't do nothing, because I'm just
testing and learning the OpenMP directives.

program test
use omp_lib
implicit none
integer :: i,j
integer, parameter :: n=361
double precision :: a(n,n), b(n,n)

call omp_set_num_threads(2)

!$omp parallel shared(a,b) private(i,j)
!$omp do
do i=1,n
   do j=1,n
       a(j,i) = dble(i)**2.d0 + dble(j)**2.d0                 !This
operations is just to spend some cpu time
       b(j,i) = dble(i)**4.d0 + dble(j)**4.d0
       a(j,i) = b(j,i)/(b(j,i)*b(j,i)) + a(j,i)/(a(j,i)*a(j,i))
   end do
end do
!$omp end do
!$omp end parallel

end program

I compile using: gfortran file.f95 - fopenmp
System: Windows XP Professional SP2
Machine: Intel Core 2 Duo E6550 2.33 GHz 2Gb RAM

The problem: If I set n = 361 the windows crashs the program, if it is
set to 360 it runs ok. Without the -fopenmp flag, I can set n up to
11169, but with 11170 it crashs. In the last case I understand that is
a memory limit problem, but in the first I don't. Why this happen? n
is to small to be memory problem.

An interesting behavior. The same program with single precision has
the limits: n=510 with -fopemmp flag and n=15795 without the flag. The
ratio 510/360 = 15795/11169 = sqrt(2).