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dlamrg.f
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*> \brief \b DLAMRG creates a permutation list to merge the entries of two independently sorted sets into a single set sorted in ascending order.
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DLAMRG + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlamrg.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlamrg.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlamrg.f">
*> [TXT]</a>
*> \endhtmlonly
*
* Definition:
* ===========
*
* SUBROUTINE DLAMRG( N1, N2, A, DTRD1, DTRD2, INDEX )
*
* .. Scalar Arguments ..
* INTEGER DTRD1, DTRD2, N1, N2
* ..
* .. Array Arguments ..
* INTEGER INDEX( * )
* DOUBLE PRECISION A( * )
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> DLAMRG will create a permutation list which will merge the elements
*> of A (which is composed of two independently sorted sets) into a
*> single set which is sorted in ascending order.
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] N1
*> \verbatim
*> N1 is INTEGER
*> \endverbatim
*>
*> \param[in] N2
*> \verbatim
*> N2 is INTEGER
*> These arguements contain the respective lengths of the two
*> sorted lists to be merged.
*> \endverbatim
*>
*> \param[in] A
*> \verbatim
*> A is DOUBLE PRECISION array, dimension (N1+N2)
*> The first N1 elements of A contain a list of numbers which
*> are sorted in either ascending or descending order. Likewise
*> for the final N2 elements.
*> \endverbatim
*>
*> \param[in] DTRD1
*> \verbatim
*> DTRD1 is INTEGER
*> \endverbatim
*>
*> \param[in] DTRD2
*> \verbatim
*> DTRD2 is INTEGER
*> These are the strides to be taken through the array A.
*> Allowable strides are 1 and -1. They indicate whether a
*> subset of A is sorted in ascending (DTRDx = 1) or descending
*> (DTRDx = -1) order.
*> \endverbatim
*>
*> \param[out] INDEX
*> \verbatim
*> INDEX is INTEGER array, dimension (N1+N2)
*> On exit this array will contain a permutation such that
*> if B( I ) = A( INDEX( I ) ) for I=1,N1+N2, then B will be
*> sorted in ascending order.
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date September 2012
*
*> \ingroup auxOTHERcomputational
*
* =====================================================================
SUBROUTINE DLAMRG( N1, N2, A, DTRD1, DTRD2, INDEX )
*
* -- LAPACK computational routine (version 3.4.2) --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
* September 2012
*
* .. Scalar Arguments ..
INTEGER DTRD1, DTRD2, N1, N2
* ..
* .. Array Arguments ..
INTEGER INDEX( * )
DOUBLE PRECISION A( * )
* ..
*
* =====================================================================
*
* .. Local Scalars ..
INTEGER I, IND1, IND2, N1SV, N2SV
* ..
* .. Executable Statements ..
*
N1SV = N1
N2SV = N2
IF( DTRD1.GT.0 ) THEN
IND1 = 1
ELSE
IND1 = N1
END IF
IF( DTRD2.GT.0 ) THEN
IND2 = 1 + N1
ELSE
IND2 = N1 + N2
END IF
I = 1
* while ( (N1SV > 0) & (N2SV > 0) )
10 CONTINUE
IF( N1SV.GT.0 .AND. N2SV.GT.0 ) THEN
IF( A( IND1 ).LE.A( IND2 ) ) THEN
INDEX( I ) = IND1
I = I + 1
IND1 = IND1 + DTRD1
N1SV = N1SV - 1
ELSE
INDEX( I ) = IND2
I = I + 1
IND2 = IND2 + DTRD2
N2SV = N2SV - 1
END IF
GO TO 10
END IF
* end while
IF( N1SV.EQ.0 ) THEN
DO 20 N1SV = 1, N2SV
INDEX( I ) = IND2
I = I + 1
IND2 = IND2 + DTRD2
20 CONTINUE
ELSE
* N2SV .EQ. 0
DO 30 N2SV = 1, N1SV
INDEX( I ) = IND1
I = I + 1
IND1 = IND1 + DTRD1
30 CONTINUE
END IF
*
RETURN
*
* End of DLAMRG
*
END

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