| 1 | module principal_cshift_m |
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| 2 | |
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| 3 | USE dimensions_mod, ONLY: iim, jjm, llm, ndm |
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| 4 | implicit none |
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| 5 | |
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| 6 | contains |
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| 7 | |
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| 8 | subroutine principal_cshift(is2, xlon, xprimm) |
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| 9 | |
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| 10 | ! Add or subtract 2 pi so that xlon is near [-pi, pi], then cshift |
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| 11 | ! so that xlon is in ascending order. Make the same cshift on |
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| 12 | ! xprimm. |
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| 13 | |
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| 14 | use nrtype, only: twopi |
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| 15 | use serre_mod, only: clon |
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| 16 | |
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| 17 | |
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| 18 | ! for iim |
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| 19 | |
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| 20 | integer, intent(in):: is2 |
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| 21 | real, intent(inout):: xlon(:), xprimm(:) ! (iim + 1) |
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| 22 | |
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| 23 | !----------------------------------------------------- |
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| 24 | |
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| 25 | if (is2 /= 0) then |
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| 26 | IF (clon <= 0.) THEN |
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| 27 | IF (is2 /= 1) THEN |
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| 28 | xlon(:is2 - 1) = xlon(:is2 - 1) + twopi |
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| 29 | xlon(:iim) = cshift(xlon(:iim), shift = is2 - 1) |
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| 30 | xprimm(:iim) = cshift(xprimm(:iim), shift = is2 - 1) |
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| 31 | END IF |
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| 32 | else |
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| 33 | xlon(is2 + 1:iim) = xlon(is2 + 1:iim) - twopi |
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| 34 | xlon(:iim) = cshift(xlon(:iim), shift = is2) |
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| 35 | xprimm(:iim) = cshift(xprimm(:iim), shift = is2) |
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| 36 | end IF |
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| 37 | end if |
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| 38 | |
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| 39 | xlon(iim + 1) = xlon(1) + twopi |
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| 40 | xprimm(iim + 1) = xprimm(1) |
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| 41 | |
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| 42 | end subroutine principal_cshift |
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| 43 | |
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| 44 | end module principal_cshift_m |
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