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44 lines
1.1 KiB
Fortran
44 lines
1.1 KiB
Fortran
*DECK DWNLT3
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SUBROUTINE DWNLT3 (I, IMAX, M, MDW, IPIVOT, H, W)
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C***BEGIN PROLOGUE DWNLT3
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C***SUBSIDIARY
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C***PURPOSE Subsidiary to WNLIT
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C***LIBRARY SLATEC
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C***TYPE DOUBLE PRECISION (WNLT3-S, DWNLT3-D)
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C***AUTHOR Hanson, R. J., (SNLA)
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C Haskell, K. H., (SNLA)
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C***DESCRIPTION
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C
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C Perform column interchange.
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C Exchange elements of permuted index vector and perform column
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C interchanges.
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C
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C***SEE ALSO DWNLIT
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C***ROUTINES CALLED DSWAP
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C***REVISION HISTORY (YYMMDD)
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C 790701 DATE WRITTEN
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C 890620 Code extracted from WNLIT and made a subroutine. (RWC))
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C 900604 DP version created from SP version. (RWC)
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C***END PROLOGUE DWNLT3
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INTEGER I, IMAX, IPIVOT(*), M, MDW
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DOUBLE PRECISION H(*), W(MDW,*)
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C
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EXTERNAL DSWAP
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C
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DOUBLE PRECISION T
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INTEGER ITEMP
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C
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C***FIRST EXECUTABLE STATEMENT DWNLT3
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IF (IMAX.NE.I) THEN
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ITEMP = IPIVOT(I)
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IPIVOT(I) = IPIVOT(IMAX)
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IPIVOT(IMAX) = ITEMP
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C
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CALL DSWAP(M, W(1,IMAX), 1, W(1,I), 1)
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C
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T = H(IMAX)
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H(IMAX) = H(I)
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H(I) = T
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ENDIF
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RETURN
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END
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