LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
dlamrg.f
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00001 *> \brief \b DLAMRG
00002 *
00003 *  =========== DOCUMENTATION ===========
00004 *
00005 * Online html documentation available at 
00006 *            http://www.netlib.org/lapack/explore-html/ 
00007 *
00008 *> \htmlonly
00009 *> Download DLAMRG + dependencies 
00010 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlamrg.f"> 
00011 *> [TGZ]</a> 
00012 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlamrg.f"> 
00013 *> [ZIP]</a> 
00014 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlamrg.f"> 
00015 *> [TXT]</a>
00016 *> \endhtmlonly 
00017 *
00018 *  Definition:
00019 *  ===========
00020 *
00021 *       SUBROUTINE DLAMRG( N1, N2, A, DTRD1, DTRD2, INDEX )
00022 * 
00023 *       .. Scalar Arguments ..
00024 *       INTEGER            DTRD1, DTRD2, N1, N2
00025 *       ..
00026 *       .. Array Arguments ..
00027 *       INTEGER            INDEX( * )
00028 *       DOUBLE PRECISION   A( * )
00029 *       ..
00030 *  
00031 *
00032 *> \par Purpose:
00033 *  =============
00034 *>
00035 *> \verbatim
00036 *>
00037 *> DLAMRG will create a permutation list which will merge the elements
00038 *> of A (which is composed of two independently sorted sets) into a
00039 *> single set which is sorted in ascending order.
00040 *> \endverbatim
00041 *
00042 *  Arguments:
00043 *  ==========
00044 *
00045 *> \param[in] N1
00046 *> \verbatim
00047 *>          N1 is INTEGER
00048 *> \endverbatim
00049 *>
00050 *> \param[in] N2
00051 *> \verbatim
00052 *>          N2 is INTEGER
00053 *>         These arguements contain the respective lengths of the two
00054 *>         sorted lists to be merged.
00055 *> \endverbatim
00056 *>
00057 *> \param[in] A
00058 *> \verbatim
00059 *>          A is DOUBLE PRECISION array, dimension (N1+N2)
00060 *>         The first N1 elements of A contain a list of numbers which
00061 *>         are sorted in either ascending or descending order.  Likewise
00062 *>         for the final N2 elements.
00063 *> \endverbatim
00064 *>
00065 *> \param[in] DTRD1
00066 *> \verbatim
00067 *>          DTRD1 is INTEGER
00068 *> \endverbatim
00069 *>
00070 *> \param[in] DTRD2
00071 *> \verbatim
00072 *>          DTRD2 is INTEGER
00073 *>         These are the strides to be taken through the array A.
00074 *>         Allowable strides are 1 and -1.  They indicate whether a
00075 *>         subset of A is sorted in ascending (DTRDx = 1) or descending
00076 *>         (DTRDx = -1) order.
00077 *> \endverbatim
00078 *>
00079 *> \param[out] INDEX
00080 *> \verbatim
00081 *>          INDEX is INTEGER array, dimension (N1+N2)
00082 *>         On exit this array will contain a permutation such that
00083 *>         if B( I ) = A( INDEX( I ) ) for I=1,N1+N2, then B will be
00084 *>         sorted in ascending order.
00085 *> \endverbatim
00086 *
00087 *  Authors:
00088 *  ========
00089 *
00090 *> \author Univ. of Tennessee 
00091 *> \author Univ. of California Berkeley 
00092 *> \author Univ. of Colorado Denver 
00093 *> \author NAG Ltd. 
00094 *
00095 *> \date November 2011
00096 *
00097 *> \ingroup auxOTHERcomputational
00098 *
00099 *  =====================================================================
00100       SUBROUTINE DLAMRG( N1, N2, A, DTRD1, DTRD2, INDEX )
00101 *
00102 *  -- LAPACK computational routine (version 3.4.0) --
00103 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
00104 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00105 *     November 2011
00106 *
00107 *     .. Scalar Arguments ..
00108       INTEGER            DTRD1, DTRD2, N1, N2
00109 *     ..
00110 *     .. Array Arguments ..
00111       INTEGER            INDEX( * )
00112       DOUBLE PRECISION   A( * )
00113 *     ..
00114 *
00115 *  =====================================================================
00116 *
00117 *     .. Local Scalars ..
00118       INTEGER            I, IND1, IND2, N1SV, N2SV
00119 *     ..
00120 *     .. Executable Statements ..
00121 *
00122       N1SV = N1
00123       N2SV = N2
00124       IF( DTRD1.GT.0 ) THEN
00125          IND1 = 1
00126       ELSE
00127          IND1 = N1
00128       END IF
00129       IF( DTRD2.GT.0 ) THEN
00130          IND2 = 1 + N1
00131       ELSE
00132          IND2 = N1 + N2
00133       END IF
00134       I = 1
00135 *     while ( (N1SV > 0) & (N2SV > 0) )
00136    10 CONTINUE
00137       IF( N1SV.GT.0 .AND. N2SV.GT.0 ) THEN
00138          IF( A( IND1 ).LE.A( IND2 ) ) THEN
00139             INDEX( I ) = IND1
00140             I = I + 1
00141             IND1 = IND1 + DTRD1
00142             N1SV = N1SV - 1
00143          ELSE
00144             INDEX( I ) = IND2
00145             I = I + 1
00146             IND2 = IND2 + DTRD2
00147             N2SV = N2SV - 1
00148          END IF
00149          GO TO 10
00150       END IF
00151 *     end while
00152       IF( N1SV.EQ.0 ) THEN
00153          DO 20 N1SV = 1, N2SV
00154             INDEX( I ) = IND2
00155             I = I + 1
00156             IND2 = IND2 + DTRD2
00157    20    CONTINUE
00158       ELSE
00159 *     N2SV .EQ. 0
00160          DO 30 N2SV = 1, N1SV
00161             INDEX( I ) = IND1
00162             I = I + 1
00163             IND1 = IND1 + DTRD1
00164    30    CONTINUE
00165       END IF
00166 *
00167       RETURN
00168 *
00169 *     End of DLAMRG
00170 *
00171       END
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