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58 lines
1.2 KiB
Fortran
58 lines
1.2 KiB
Fortran
subroutine ave_error(x,n,ave,err)
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implicit none
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integer, intent(in) :: n
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double precision, intent(in) :: x(n)
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double precision, intent(out) :: ave, err
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double precision :: variance
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if (n < 1) then
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stop 'n<1 in ave_error'
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else if (n == 1) then
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ave = x(1)
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err = 0.d0
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else
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ave = sum(x(:)) / dble(n)
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variance = sum((x(:) - ave)**2) / dble(n-1)
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err = dsqrt(variance/dble(n))
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endif
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end subroutine ave_error
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subroutine random_gauss(z,n)
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implicit none
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integer, intent(in) :: n
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double precision, intent(out) :: z(n)
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double precision :: u(n+1)
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double precision, parameter :: two_pi = 2.d0*dacos(-1.d0)
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integer :: i
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call random_number(u)
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if (iand(n,1) == 0) then
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! n is even
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do i=1,n,2
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z(i) = dsqrt(-2.d0*dlog(u(i)))
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z(i+1) = z(i) * dsin( two_pi*u(i+1) )
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z(i) = z(i) * dcos( two_pi*u(i+1) )
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end do
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else
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! n is odd
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do i=1,n-1,2
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z(i) = dsqrt(-2.d0*dlog(u(i)))
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z(i+1) = z(i) * dsin( two_pi*u(i+1) )
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z(i) = z(i) * dcos( two_pi*u(i+1) )
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end do
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z(n) = dsqrt(-2.d0*dlog(u(n)))
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z(n) = z(n) * dcos( two_pi*u(n+1) )
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end if
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end subroutine random_gauss
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