46 lines
1 KiB
Forth
46 lines
1 KiB
Forth
module triples
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implicit none
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integer :: max_peri, prim, total
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integer :: u(9,3) = reshape((/ 1, -2, 2, 2, -1, 2, 2, -2, 3, &
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1, 2, 2, 2, 1, 2, 2, 2, 3, &
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-1, 2, 2, -2, 1, 2, -2, 2, 3 /), &
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(/ 9, 3 /))
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contains
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recursive subroutine new_tri(in)
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integer, intent(in) :: in(:)
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integer :: i
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integer :: t(3), p
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p = sum(in)
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if (p > max_peri) return
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prim = prim + 1
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total = total + max_peri / p
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do i = 1, 3
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t(1) = sum(u(1:3, i) * in)
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t(2) = sum(u(4:6, i) * in)
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t(3) = sum(u(7:9, i) * in)
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call new_tri(t);
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end do
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end subroutine new_tri
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end module triples
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program Pythagorean
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use triples
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implicit none
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integer :: seed(3) = (/ 3, 4, 5 /)
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max_peri = 10
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do
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total = 0
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prim = 0
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call new_tri(seed)
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write(*, "(a, i10, 2(i10, a))") "Up to", max_peri, total, " triples", prim, " primitives"
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if(max_peri == 100000000) exit
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max_peri = max_peri * 10
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end do
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end program Pythagorean
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