152 lines
3.4 KiB
Fortran
152 lines
3.4 KiB
Fortran
*> \brief \b SLAORD
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*
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* =========== DOCUMENTATION ===========
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*
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* Online html documentation available at
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* http://www.netlib.org/lapack/explore-html/
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*
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* Definition:
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* ===========
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*
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* SUBROUTINE SLAORD( JOB, N, X, INCX )
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*
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* .. Scalar Arguments ..
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* CHARACTER JOB
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* INTEGER INCX, N
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* ..
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* .. Array Arguments ..
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* REAL X( * )
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* ..
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*
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*
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*> \par Purpose:
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* =============
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*>
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*> \verbatim
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*>
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*> SLAORD sorts the elements of a vector x in increasing or decreasing
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*> order.
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*> \endverbatim
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*
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* Arguments:
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* ==========
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*
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*> \param[in] JOB
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*> \verbatim
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*> JOB is CHARACTER
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*> = 'I': Sort in increasing order
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*> = 'D': Sort in decreasing order
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*> \endverbatim
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*>
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*> \param[in] N
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*> \verbatim
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*> N is INTEGER
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*> The length of the vector X.
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*> \endverbatim
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*>
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*> \param[in,out] X
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*> \verbatim
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*> X is REAL array, dimension
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*> (1+(N-1)*INCX)
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*> On entry, the vector of length n to be sorted.
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*> On exit, the vector x is sorted in the prescribed order.
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*> \endverbatim
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*>
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*> \param[in] INCX
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*> \verbatim
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*> INCX is INTEGER
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*> The spacing between successive elements of X. INCX >= 0.
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*> \endverbatim
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*
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* Authors:
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* ========
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*
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*> \author Univ. of Tennessee
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*> \author Univ. of California Berkeley
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*> \author Univ. of Colorado Denver
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*> \author NAG Ltd.
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*
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*> \date November 2011
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*
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*> \ingroup single_lin
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*
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* =====================================================================
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SUBROUTINE SLAORD( JOB, N, X, INCX )
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*
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* -- LAPACK test routine (version 3.4.0) --
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* -- LAPACK is a software package provided by Univ. of Tennessee, --
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* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
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* November 2011
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*
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* .. Scalar Arguments ..
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CHARACTER JOB
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INTEGER INCX, N
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* ..
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* .. Array Arguments ..
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REAL X( * )
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* ..
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*
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* =====================================================================
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*
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* .. Local Scalars ..
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INTEGER I, INC, IX, IXNEXT
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REAL TEMP
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* ..
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* .. External Functions ..
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LOGICAL LSAME
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EXTERNAL LSAME
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* ..
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* .. Intrinsic Functions ..
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INTRINSIC ABS
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* ..
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* .. Executable Statements ..
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*
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INC = ABS( INCX )
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IF( LSAME( JOB, 'I' ) ) THEN
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*
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* Sort in increasing order
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*
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DO 20 I = 2, N
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IX = 1 + ( I-1 )*INC
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10 CONTINUE
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IF( IX.EQ.1 )
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$ GO TO 20
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IXNEXT = IX - INC
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IF( X( IX ).GT.X( IXNEXT ) ) THEN
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GO TO 20
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ELSE
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TEMP = X( IX )
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X( IX ) = X( IXNEXT )
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X( IXNEXT ) = TEMP
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END IF
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IX = IXNEXT
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GO TO 10
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20 CONTINUE
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*
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ELSE IF( LSAME( JOB, 'D' ) ) THEN
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*
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* Sort in decreasing order
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*
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DO 40 I = 2, N
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IX = 1 + ( I-1 )*INC
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30 CONTINUE
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IF( IX.EQ.1 )
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$ GO TO 40
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IXNEXT = IX - INC
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IF( X( IX ).LT.X( IXNEXT ) ) THEN
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GO TO 40
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ELSE
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TEMP = X( IX )
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X( IX ) = X( IXNEXT )
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X( IXNEXT ) = TEMP
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END IF
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IX = IXNEXT
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GO TO 30
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40 CONTINUE
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END IF
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RETURN
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*
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* End of SLAORD
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*
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END
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