Last change
on this file since 4321 was
2696,
checked in by kanani, 7 years ago
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Merge of branch palm4u into trunk
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File size:
1.2 KB
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1 | C --- Plain QSSA with fixed step size |
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2 | C |
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3 | SUBROUTINE INTEGRATE( TIN, TOUT ) |
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4 | |
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5 | INCLUDE 'KPP_ROOT_params.h' |
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6 | INCLUDE 'KPP_ROOT_global.h' |
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7 | |
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8 | C TIN - Start Time |
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9 | KPP_REAL TIN |
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10 | C TOUT - End Time |
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11 | KPP_REAL TOUT |
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12 | |
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13 | C Local variables |
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14 | KPP_REAL P_VAR(NVAR), D_VAR(NVAR) |
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15 | LOGICAL IsReject |
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16 | KPP_REAL T, Tnext, STEP, Told, SUP |
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17 | KPP_REAL ratio, tmp |
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18 | INTEGER i |
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19 | |
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20 | T = TIN |
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21 | Tnext = TOUT |
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22 | STEP = 0.1 |
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23 | Told = T |
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24 | SUP = 1e-14 |
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25 | IsReject = .false. |
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26 | |
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27 | C -- BELOW THIS LIMIT USE TAYLOR INSTEAD OF EXP --- |
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28 | |
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29 | do while ( T.lt.Tnext ) |
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30 | |
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31 | if ( T.gt.Tnext ) then |
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32 | STEP = Tnext - Told |
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33 | T = Tnext |
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34 | end if |
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35 | |
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36 | CALL FSPLIT_VAR ( VAR, P_VAR, D_VAR ) |
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37 | |
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38 | do i=1,NVAR |
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39 | if ( abs(D_VAR(i)).gt.SUP ) then |
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40 | ratio = P_VAR(i)/D_VAR(i) |
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41 | tmp = exp(-D_VAR(i)*STEP) |
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42 | VAR(i) = tmp * (VAR(i) - ratio) + ratio |
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43 | else |
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44 | tmp = D_VAR(i) * STEP |
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45 | VAR(i) = VAR(i) + P_VAR(i) * 0.5 * STEP * ( 1 - 0.5 * tmp * |
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46 | * ( 1 - 1.0 / 3.0 * tmp ) ) |
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47 | end if |
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48 | end do |
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49 | |
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50 | T = T + STEP |
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51 | TIME = T |
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52 | |
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53 | end do |
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54 | |
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55 | RETURN |
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56 | END |
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