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131 lines
3.3 KiB
131 lines
3.3 KiB
2 years ago
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C Copyright(C) 1999-2020 National Technology & Engineering Solutions
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C of Sandia, LLC (NTESS). Under the terms of Contract DE-NA0003525 with
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C NTESS, the U.S. Government retains certain rights in this software.
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C
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C See packages/seacas/LICENSE for details
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SUBROUTINE SRCHGE( LBLK,NE,X,IND,XV,IMIN,IMAX,NDIM,I,
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* IL,IU,IT,INDX1,INDX2,XTST )
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C-----------------------------------------------------------------------
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C DESCRIPTION:
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C PERFORM A BINARY SEARCH TO FIND THE ELEMENT NUMBER I
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C OF A SORTED ARRAY FOR WHICH ALL ELEMENTS AT I OR ABOVE ARE
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C GREATER OR EQUAL TO THAN SOME VALUE XV,
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C WHILE ALL ELEMENTS BELOW I ARE LESS THAN THE VALUE.
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C X(I-2) X(I-1) X(I) X(I+1) X(I+2)
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C XV X>
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C ASSUMED THAT THE ARRAY X HAS BEEN SORTED IN INCREASING ORDER,
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C BUT THE ELEMENTS HAVE NOT BEEN MOVED.
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C THE SORTED LIST IS DETERMINED BY THE ARRAY INDX,
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C WHICH POSITIONS THE ORIGINAL UNSORTED X ARRAY ELEMENTS
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C IN THE SORTED LIST. THUS, THE 5TH ELEMENT IN THE SORTED LIST IS
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C X(IND(5))
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C-----------------------------------------------------------------------
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C INPUT:
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C X - ARRAY IN UNSORTED ORDER
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C IND - INDEX ARRAY GIVING THE ELEMENT ORDER IN THE SORTED LIST
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C XV - X VALUE TO TEST AGAINST
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C IMIN - THE LOWEST NUMBERED POSITION IN THE SORTED LIST TO TEST
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C IMAX - THE HIGHEST NUMBERED POSITION IN THE SORTED LIST TO TEST
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C NDIM - THE DIMENSION OF THE ARRAYS
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C OUTPUT:
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C I - THE FIRST POSITION IN THE SORTED LIST .GT. XV
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C SCRATCH:
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C IL
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C IU
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C IT
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C INDX1
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C INDX2
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C XTST
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C-----------------------------------------------------------------------
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DIMENSION
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* X(NDIM), IND(NDIM), XV(LBLK), I(LBLK)
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DIMENSION
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* IL(LBLK),IU(LBLK),IT(LBLK),INDX1(LBLK),INDX2(LBLK),
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* XTST(LBLK)
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IF (IMAX.EQ.0.OR.NDIM.EQ.0) THEN
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DO J = 1, NE
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I(J) = 0
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ENDDO
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RETURN
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ENDIF
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DO 25 J = 1, NE
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IL(J) = IMIN
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IU(J) = IMAX
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INDX1(J) = J
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25 CONTINUE
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ILOOP = NE
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1000 CONTINUE
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DO 50 JJ = 1, ILOOP
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INDX2(JJ) = INDX1(JJ)
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J = INDX1(JJ)
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IT(J) = (IU(J) + IL(J)) / 2
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50 CONTINUE
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DO 35 J = 1, NE
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XTST(J) = X( IND(IT(J)) )
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35 CONTINUE
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IF ( ILOOP .GT. 64) THEN
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ILP = 0
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DO 60 JJ = 1, ILOOP
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J = INDX2(JJ)
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IF( XTST(J) .LT. XV(J) )THEN
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IL(J) =IT(J) + 1
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ELSE
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IU(J) =IT(J) - 1
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ENDIF
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IF( IL(J) .LE. IU(J)) THEN
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ILP = ILP + 1
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INDX1(ILP) = J
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ENDIF
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60 CONTINUE
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ELSE
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ILP = 0
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DO 51 JJ = 1, ILOOP
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J = INDX2(JJ)
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IF( XTST(J) .LT. XV(J) )THEN
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IL(J) =IT(J) + 1
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ELSE
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IU(J) =IT(J) - 1
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ENDIF
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IF( IL(J) .LE. IU(J)) THEN
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ILP = ILP + 1
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INDX1(ILP) = J
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ENDIF
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51 CONTINUE
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ENDIF
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ILOOP = ILP
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IF(ILOOP .NE. 0 )GO TO 1000
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C RANGE HAD NARROWED TO 1 LOCATION. HOWEVER, THE POINT LAST TESTED
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C COULD BE ABOVE, BELOW, OR ON THE SEARCH POINT. CHECK FOR PROPER CASE
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DO 200 J = 1, NE
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IF( XTST(J) .LT. XV(J) )THEN
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I(J) = IT(J) + 1
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ELSE
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I(J) = IT(J)
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ENDIF
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200 CONTINUE
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RETURN
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END
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