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1 C Work performed under the auspices of the U.S. Department of Energy |
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2 C by Lawrence Livermore National Laboratory under contract number |
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3 C W-7405-Eng-48. |
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4 C |
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5 SUBROUTINE DCNST0 (NEQ, Y, ICNSTR, IRET) |
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6 C |
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7 C***BEGIN PROLOGUE DCNST0 |
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8 C***DATE WRITTEN 950808 (YYMMDD) |
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9 C***REVISION DATE 950808 (YYMMDD) |
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10 C |
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11 C |
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12 C----------------------------------------------------------------------- |
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13 C***DESCRIPTION |
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14 C |
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15 C This subroutine checks for constraint violations in the initial |
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16 C approximate solution u. |
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17 C |
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18 C On entry |
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19 C |
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20 C NEQ -- size of the nonlinear system, and the length of arrays |
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21 C Y and ICNSTR. |
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22 C |
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23 C Y -- real array containing the initial approximate root. |
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24 C |
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25 C ICNSTR -- INTEGER array of length NEQ containing flags indicating |
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26 C which entries in Y are to be constrained. |
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27 C if ICNSTR(I) = 2, then Y(I) must be .GT. 0, |
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28 C if ICNSTR(I) = 1, then Y(I) must be .GE. 0, |
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29 C if ICNSTR(I) = -1, then Y(I) must be .LE. 0, while |
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30 C if ICNSTR(I) = -2, then Y(I) must be .LT. 0, while |
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31 C if ICNSTR(I) = 0, then Y(I) is not constrained. |
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32 C |
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33 C On return |
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34 C |
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35 C IRET -- output flag. |
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36 C IRET=0 means that u satisfied all constraints. |
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37 C IRET.NE.0 means that Y(IRET) failed to satisfy its |
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38 C constraint. |
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39 C |
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40 C----------------------------------------------------------------------- |
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41 IMPLICIT DOUBLE PRECISION(A-H,O-Z) |
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42 DIMENSION Y(NEQ), ICNSTR(NEQ) |
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43 SAVE ZERO |
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44 DATA ZERO/0.D0/ |
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45 C----------------------------------------------------------------------- |
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46 C Check constraints for initial Y. If a constraint has been violated, |
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47 C set IRET = I to signal an error return to calling routine. |
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48 C----------------------------------------------------------------------- |
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49 IRET = 0 |
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50 DO 100 I = 1,NEQ |
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51 IF (ICNSTR(I) .EQ. 2) THEN |
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52 IF (Y(I) .LE. ZERO) THEN |
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53 IRET = I |
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54 RETURN |
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55 ENDIF |
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56 ELSEIF (ICNSTR(I) .EQ. 1) THEN |
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57 IF (Y(I) .LT. ZERO) THEN |
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58 IRET = I |
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59 RETURN |
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60 ENDIF |
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61 ELSEIF (ICNSTR(I) .EQ. -1) THEN |
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62 IF (Y(I) .GT. ZERO) THEN |
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63 IRET = I |
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64 RETURN |
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65 ENDIF |
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66 ELSEIF (ICNSTR(I) .EQ. -2) THEN |
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67 IF (Y(I) .GE. ZERO) THEN |
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68 IRET = I |
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69 RETURN |
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70 ENDIF |
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71 ENDIF |
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72 100 CONTINUE |
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73 RETURN |
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74 C----------------------- END OF SUBROUTINE DCNST0 ---------------------- |
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75 END |
