convert linalg library from Fortran to C++
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Axel Kohlmeyer
168
lib/linalg/fortran/dlamrg.f
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168
lib/linalg/fortran/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.
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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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*> \htmlonly
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*> Download DLAMRG + dependencies
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlamrg.f">
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*> [TGZ]</a>
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlamrg.f">
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*> [ZIP]</a>
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlamrg.f">
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*> [TXT]</a>
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*> \endhtmlonly
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*
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* Definition:
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* ===========
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*
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* SUBROUTINE DLAMRG( N1, N2, A, DTRD1, DTRD2, INDEX )
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*
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* .. Scalar Arguments ..
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* INTEGER DTRD1, DTRD2, N1, N2
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* ..
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* .. Array Arguments ..
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* INTEGER INDEX( * )
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* DOUBLE PRECISION A( * )
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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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*> DLAMRG will create a permutation list which will merge the elements
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*> of A (which is composed of two independently sorted sets) into a
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*> single set which is sorted in ascending 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] N1
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*> \verbatim
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*> N1 is INTEGER
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*> \endverbatim
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*>
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*> \param[in] N2
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*> \verbatim
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*> N2 is INTEGER
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*> These arguments contain the respective lengths of the two
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*> sorted lists to be merged.
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*> \endverbatim
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*>
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*> \param[in] A
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*> \verbatim
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*> A is DOUBLE PRECISION array, dimension (N1+N2)
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*> The first N1 elements of A contain a list of numbers which
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*> are sorted in either ascending or descending order. Likewise
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*> for the final N2 elements.
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*> \endverbatim
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*>
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*> \param[in] DTRD1
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*> \verbatim
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*> DTRD1 is INTEGER
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*> \endverbatim
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*>
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*> \param[in] DTRD2
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*> \verbatim
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*> DTRD2 is INTEGER
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*> These are the strides to be taken through the array A.
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*> Allowable strides are 1 and -1. They indicate whether a
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*> subset of A is sorted in ascending (DTRDx = 1) or descending
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*> (DTRDx = -1) order.
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*> \endverbatim
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*>
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*> \param[out] INDEX
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*> \verbatim
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*> INDEX is INTEGER array, dimension (N1+N2)
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*> On exit this array will contain a permutation such that
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*> if B( I ) = A( INDEX( I ) ) for I=1,N1+N2, then B will be
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*> sorted in ascending order.
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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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*> \ingroup auxOTHERcomputational
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*
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* =====================================================================
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SUBROUTINE DLAMRG( N1, N2, A, DTRD1, DTRD2, INDEX )
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*
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* -- LAPACK computational routine --
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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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*
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* .. Scalar Arguments ..
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INTEGER DTRD1, DTRD2, N1, N2
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* ..
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* .. Array Arguments ..
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INTEGER INDEX( * )
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DOUBLE PRECISION A( * )
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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, IND1, IND2, N1SV, N2SV
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* ..
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* .. Executable Statements ..
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*
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N1SV = N1
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N2SV = N2
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IF( DTRD1.GT.0 ) THEN
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IND1 = 1
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ELSE
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IND1 = N1
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END IF
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IF( DTRD2.GT.0 ) THEN
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IND2 = 1 + N1
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ELSE
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IND2 = N1 + N2
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END IF
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I = 1
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* while ( (N1SV > 0) & (N2SV > 0) )
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10 CONTINUE
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IF( N1SV.GT.0 .AND. N2SV.GT.0 ) THEN
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IF( A( IND1 ).LE.A( IND2 ) ) THEN
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INDEX( I ) = IND1
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I = I + 1
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IND1 = IND1 + DTRD1
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N1SV = N1SV - 1
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ELSE
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INDEX( I ) = IND2
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I = I + 1
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IND2 = IND2 + DTRD2
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N2SV = N2SV - 1
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END IF
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GO TO 10
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END IF
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* end while
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IF( N1SV.EQ.0 ) THEN
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DO 20 N1SV = 1, N2SV
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INDEX( I ) = IND2
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I = I + 1
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IND2 = IND2 + DTRD2
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20 CONTINUE
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ELSE
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* N2SV .EQ. 0
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DO 30 N2SV = 1, N1SV
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INDEX( I ) = IND1
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I = I + 1
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IND1 = IND1 + DTRD1
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30 CONTINUE
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END IF
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*
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RETURN
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*
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* End of DLAMRG
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*
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END
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