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47 lines
1.0 KiB
Fortran
47 lines
1.0 KiB
Fortran
BEGIN_PROVIDER [ double precision, halton_seed, (3) ]
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implicit none
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BEGIN_DOC
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! Seed of the quasi Monte Carlo sequence generator
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END_DOC
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halton_seed(:) = 1.d0
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END_PROVIDER
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BEGIN_PROVIDER [ double precision, halton_base, (3) ]
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implicit none
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BEGIN_DOC
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! Base of the quasi Monte Carlo sequence generator
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END_DOC
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halton_base(1) = 2.d0
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halton_base(2) = 3.d0
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halton_base(3) = 5.d0
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END_PROVIDER
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double precision function halton_ranf(axis)
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implicit none
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integer, intent(in) :: axis
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!call random_number(halton_ranf)
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!return
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ASSERT (axis > 0)
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ASSERT (axis <= 3)
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double precision :: l_seed
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l_seed = halton_seed(axis)
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halton_seed(axis) += 1_8
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halton_ranf = 0.d0
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double precision :: base_inv, base_inv0
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base_inv = 1.d0/halton_base(axis)
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base_inv0 = 1.d0/halton_base(axis)
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do while (l_seed > 0.d0)
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halton_ranf = halton_ranf + dble(mod(int(l_seed),int(halton_base(axis)))) * base_inv
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base_inv *= base_inv0
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l_seed *= base_inv0
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enddo
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end
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