| [1403] | 1 | ! $Id: lmdz_ran1.f90 5117 2024-07-24 14:23:34Z abarral $ |
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| [5099] | 2 | |
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| [5117] | 3 | MODULE lmdz_ran1 |
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| 4 | IMPLICIT NONE; PRIVATE |
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| 5 | PUBLIC ran1 |
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| 6 | CONTAINS |
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| [2197] | 7 | |
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| [5117] | 8 | FUNCTION RAN1(IDUM) |
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| 9 | IMPLICIT NONE |
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| 10 | REAL :: RAN1 |
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| 11 | REAL, SAVE :: R(97) |
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| 12 | REAL, PARAMETER :: RM1 = 3.8580247E-6, RM2 = 7.4373773E-6 |
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| 13 | INTEGER, SAVE :: IFF = 0 |
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| 14 | INTEGER, save :: ix1, ix2, ix3 |
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| 15 | INTEGER, PARAMETER :: M1 = 259200, IA1 = 7141, IC1 = 54773 |
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| 16 | INTEGER, PARAMETER :: M2 = 134456, IA2 = 8121, IC2 = 28411 |
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| 17 | INTEGER, PARAMETER :: M3 = 243000, IA3 = 4561, IC3 = 51349 |
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| 18 | INTEGER :: IDUM, J |
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| [5105] | 19 | |
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| [5117] | 20 | IF (IDUM<0.OR.IFF==0) THEN |
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| 21 | IFF = 1 |
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| 22 | IX1 = MOD(IC1 - IDUM, M1) |
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| 23 | IX1 = MOD(IA1 * IX1 + IC1, M1) |
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| 24 | IX2 = MOD(IX1, M2) |
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| 25 | IX1 = MOD(IA1 * IX1 + IC1, M1) |
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| 26 | IX3 = MOD(IX1, M3) |
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| 27 | DO J = 1, 97 |
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| 28 | IX1 = MOD(IA1 * IX1 + IC1, M1) |
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| 29 | IX2 = MOD(IA2 * IX2 + IC2, M2) |
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| 30 | R(J) = (REAL(IX1) + REAL(IX2) * RM2) * RM1 |
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| 31 | END DO |
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| 32 | IDUM = 1 |
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| 33 | ENDIF |
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| 34 | IX1 = MOD(IA1 * IX1 + IC1, M1) |
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| 35 | IX2 = MOD(IA2 * IX2 + IC2, M2) |
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| 36 | IX3 = MOD(IA3 * IX3 + IC3, M3) |
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| 37 | J = 1 + (97 * IX3) / M3 |
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| 38 | IF(J>97.OR.J<1) stop 1 |
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| 39 | RAN1 = R(J) |
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| 40 | R(J) = (REAL(IX1) + REAL(IX2) * RM2) * RM1 |
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| 41 | |
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| 42 | END FUNCTION RAN1 |
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| 43 | END MODULE lmdz_ran1 |
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