| 1 | MODULE solsor |
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| 2 | !!====================================================================== |
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| 3 | !! *** MODULE solsor *** |
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| 4 | !! Ocean solver : Successive Over-Relaxation solver |
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| 5 | !!===================================================================== |
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| 6 | |
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| 7 | !!---------------------------------------------------------------------- |
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| 8 | !! sol_sor : Red-Black Successive Over-Relaxation solver |
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| 9 | !!---------------------------------------------------------------------- |
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| 10 | !! * Modules used |
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| 11 | USE oce ! ocean dynamics and tracers variables |
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| 12 | USE dom_oce ! ocean space and time domain variables |
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| 13 | USE zdf_oce ! ocean vertical physics variables |
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| 14 | USE sol_oce ! solver variables |
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| 15 | USE in_out_manager ! I/O manager |
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| 16 | USE lib_mpp ! distributed memory computing |
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| 17 | USE lbclnk ! ocean lateral boundary conditions (or mpp link) |
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| 18 | |
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| 19 | IMPLICIT NONE |
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| 20 | PRIVATE |
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| 21 | |
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| 22 | !! * Routine accessibility |
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| 23 | PUBLIC sol_sor ! ??? |
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| 24 | |
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| 25 | !!---------------------------------------------------------------------- |
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| 26 | !! OPA 9.0 , LODYC-IPSL (2003) |
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| 27 | !!---------------------------------------------------------------------- |
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| 28 | |
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| 29 | CONTAINS |
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| 30 | |
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| 31 | SUBROUTINE sol_sor( kindic ) |
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| 32 | !!---------------------------------------------------------------------- |
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| 33 | !! *** ROUTINE sol_sor *** |
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| 34 | !! |
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| 35 | !! ** Purpose : Solve the ellipic equation for the barotropic stream |
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| 36 | !! function system (lk_dynspg_rl=T) or the transport divergence |
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| 37 | !! system (lk_dynspg_fsc=T) using a red-black successive-over- |
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| 38 | !! relaxation method. |
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| 39 | !! In the former case, the barotropic stream function trend has a |
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| 40 | !! zero boundary condition along all coastlines (i.e. continent |
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| 41 | !! as well as islands) while in the latter the boundary condition |
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| 42 | !! specification is not required. |
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| 43 | !! |
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| 44 | !! ** Method : Successive-over-relaxation method using the red-black |
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| 45 | !! technique. The former technique used was not compatible with |
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| 46 | !! the north-fold boundary condition used in orca configurations. |
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| 47 | !! |
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| 48 | !! References : |
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| 49 | !! Madec et al. 1988, Ocean Modelling, issue 78, 1-6. |
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| 50 | !! |
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| 51 | !! History : |
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| 52 | !! ! 90-10 (G. Madec) Original code |
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| 53 | !! ! 91-11 (G. Madec) |
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| 54 | !! 7.1 ! 93-04 (G. Madec) time filter |
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| 55 | !! ! 96-05 (G. Madec) merge sor and pcg formulations |
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| 56 | !! ! 96-11 (A. Weaver) correction to preconditioning |
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| 57 | !! 9.0 ! 03-04 (C. Deltel, G. Madec) Red-Black SOR in free form |
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| 58 | !!---------------------------------------------------------------------- |
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| 59 | !! * Arguments |
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| 60 | INTEGER, INTENT( inout ) :: kindic ! solver indicator, < 0 if the conver- |
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| 61 | ! ! gence is not reached: the model is |
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| 62 | ! ! stopped in step |
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| 63 | ! ! set to zero before the call of solsor |
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| 64 | !! * Local declarations |
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| 65 | INTEGER :: ji, jj, jn ! dummy loop indices |
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| 66 | INTEGER :: ishift |
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| 67 | REAL(wp) :: ztmp, zres, zres2 |
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| 68 | |
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| 69 | INTEGER :: ijmppodd, ijmppeven |
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| 70 | !!---------------------------------------------------------------------- |
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| 71 | |
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| 72 | ijmppeven = MOD(nimpp+njmpp ,2) |
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| 73 | ijmppodd = MOD(nimpp+njmpp+1,2) |
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| 74 | ! ! ============== |
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| 75 | DO jn = 1, nmax ! Iterative loop |
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| 76 | ! ! ============== |
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| 77 | |
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| 78 | CALL lbc_lnk( gcx, c_solver_pt, 1. ) ! applied the lateral boundary conditions |
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| 79 | |
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| 80 | ! Residus |
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| 81 | ! ------- |
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| 82 | |
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| 83 | ! Guess black update |
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| 84 | DO jj = 2, jpjm1 |
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| 85 | ishift = MOD( jj-ijmppodd, 2 ) |
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| 86 | DO ji = 2+ishift, jpim1, 2 |
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| 87 | ztmp = gcb(ji ,jj ) & |
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| 88 | & - gcp(ji,jj,1) * gcx(ji ,jj-1) & |
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| 89 | & - gcp(ji,jj,2) * gcx(ji-1,jj ) & |
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| 90 | & - gcp(ji,jj,3) * gcx(ji+1,jj ) & |
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| 91 | & - gcp(ji,jj,4) * gcx(ji ,jj+1) |
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| 92 | ! Estimate of the residual |
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| 93 | zres = ztmp - gcx(ji,jj) |
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| 94 | gcr(ji,jj) = zres * gcdmat(ji,jj) * zres |
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| 95 | ! Guess update |
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| 96 | gcx(ji,jj) = sor * ztmp + (1-sor) * gcx(ji,jj) |
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| 97 | END DO |
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| 98 | END DO |
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| 99 | |
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| 100 | CALL lbc_lnk( gcx, c_solver_pt, 1. ) ! applied the lateral boubary conditions |
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| 101 | |
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| 102 | ! Guess red update |
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| 103 | DO jj = 2, jpjm1 |
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| 104 | ishift = MOD( jj-ijmppeven, 2 ) |
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| 105 | DO ji = 2+ishift, jpim1, 2 |
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| 106 | ztmp = gcb(ji ,jj ) & |
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| 107 | & - gcp(ji,jj,1) * gcx(ji ,jj-1) & |
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| 108 | & - gcp(ji,jj,2) * gcx(ji-1,jj ) & |
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| 109 | & - gcp(ji,jj,3) * gcx(ji+1,jj ) & |
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| 110 | & - gcp(ji,jj,4) * gcx(ji ,jj+1) |
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| 111 | ! Estimate of the residual |
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| 112 | zres = ztmp - gcx(ji,jj) |
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| 113 | gcr(ji,jj) = zres * gcdmat(ji,jj) * zres |
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| 114 | ! Guess update |
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| 115 | gcx(ji,jj) = sor * ztmp + (1-sor) * gcx(ji,jj) |
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| 116 | END DO |
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| 117 | END DO |
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| 118 | |
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| 119 | ! test of convergence |
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| 120 | IF ( jn > nmin .AND. MOD( jn-nmin, nmod ) == 0 ) then |
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| 121 | |
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| 122 | SELECT CASE ( nsol_arp ) |
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| 123 | CASE ( 0 ) ! absolute precision (maximum value of the residual) |
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| 124 | zres2 = MAXVAL( gcr(2:jpim1,2:jpjm1) ) |
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| 125 | IF( lk_mpp ) CALL mpp_max( zres2 ) ! max over the global domain |
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| 126 | ! test of convergence |
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| 127 | IF( zres2 < resmax .OR. jn == nmax ) THEN |
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| 128 | res = SQRT( zres2 ) |
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| 129 | niter = jn |
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| 130 | ncut = 999 |
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| 131 | ENDIF |
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| 132 | CASE ( 1 ) ! relative precision |
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| 133 | rnorme = SUM( gcr(2:jpim1,2:jpjm1) ) |
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| 134 | IF( lk_mpp ) CALL mpp_sum( rnorme ) ! sum over the global domain |
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| 135 | ! test of convergence |
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| 136 | IF( rnorme < epsr .OR. jn == nmax ) THEN |
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| 137 | res = SQRT( rnorme ) |
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| 138 | niter = jn |
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| 139 | ncut = 999 |
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| 140 | ENDIF |
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| 141 | END SELECT |
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| 142 | |
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| 143 | !**** |
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| 144 | ! IF(lwp)WRITE(numsol,9300) jn, res, sqrt( epsr ) / eps |
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| 145 | 9300 FORMAT(' niter :',i4,' res :',e20.10,' b :',e20.10) |
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| 146 | !**** |
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| 147 | |
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| 148 | ENDIF |
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| 149 | ! indicator of non-convergence or explosion |
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| 150 | IF( jn == nmax .OR. SQRT(epsr)/eps > 1.e+20 ) kindic = -2 |
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| 151 | IF( ncut == 999 ) GOTO 999 |
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| 152 | |
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| 153 | ! ! ===================== |
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| 154 | END DO ! END of iterative loop |
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| 155 | ! ! ===================== |
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| 156 | |
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| 157 | 999 CONTINUE |
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| 158 | |
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| 159 | |
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| 160 | ! Output in gcx |
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| 161 | ! ------------- |
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| 162 | |
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| 163 | CALL lbc_lnk( gcx, c_solver_pt, 1. ) ! boundary conditions |
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| 164 | |
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| 165 | |
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| 166 | END SUBROUTINE sol_sor |
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| 167 | |
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| 168 | !!===================================================================== |
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| 169 | END MODULE solsor |
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