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Annotation of rpl/lapack/lapack/dlamrg.f, revision 1.9

1.8       bertrand    1: *> \brief \b DLAMRG
                      2: *
                      3: *  =========== DOCUMENTATION ===========
                      4: *
                      5: * Online html documentation available at 
                      6: *            http://www.netlib.org/lapack/explore-html/ 
                      7: *
                      8: *> \htmlonly
                      9: *> Download DLAMRG + dependencies 
                     10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlamrg.f"> 
                     11: *> [TGZ]</a> 
                     12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlamrg.f"> 
                     13: *> [ZIP]</a> 
                     14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlamrg.f"> 
                     15: *> [TXT]</a>
                     16: *> \endhtmlonly 
                     17: *
                     18: *  Definition:
                     19: *  ===========
                     20: *
                     21: *       SUBROUTINE DLAMRG( N1, N2, A, DTRD1, DTRD2, INDEX )
                     22: * 
                     23: *       .. Scalar Arguments ..
                     24: *       INTEGER            DTRD1, DTRD2, N1, N2
                     25: *       ..
                     26: *       .. Array Arguments ..
                     27: *       INTEGER            INDEX( * )
                     28: *       DOUBLE PRECISION   A( * )
                     29: *       ..
                     30: *  
                     31: *
                     32: *> \par Purpose:
                     33: *  =============
                     34: *>
                     35: *> \verbatim
                     36: *>
                     37: *> DLAMRG will create a permutation list which will merge the elements
                     38: *> of A (which is composed of two independently sorted sets) into a
                     39: *> single set which is sorted in ascending order.
                     40: *> \endverbatim
                     41: *
                     42: *  Arguments:
                     43: *  ==========
                     44: *
                     45: *> \param[in] N1
                     46: *> \verbatim
                     47: *>          N1 is INTEGER
                     48: *> \endverbatim
                     49: *>
                     50: *> \param[in] N2
                     51: *> \verbatim
                     52: *>          N2 is INTEGER
                     53: *>         These arguements contain the respective lengths of the two
                     54: *>         sorted lists to be merged.
                     55: *> \endverbatim
                     56: *>
                     57: *> \param[in] A
                     58: *> \verbatim
                     59: *>          A is DOUBLE PRECISION array, dimension (N1+N2)
                     60: *>         The first N1 elements of A contain a list of numbers which
                     61: *>         are sorted in either ascending or descending order.  Likewise
                     62: *>         for the final N2 elements.
                     63: *> \endverbatim
                     64: *>
                     65: *> \param[in] DTRD1
                     66: *> \verbatim
                     67: *>          DTRD1 is INTEGER
                     68: *> \endverbatim
                     69: *>
                     70: *> \param[in] DTRD2
                     71: *> \verbatim
                     72: *>          DTRD2 is INTEGER
                     73: *>         These are the strides to be taken through the array A.
                     74: *>         Allowable strides are 1 and -1.  They indicate whether a
                     75: *>         subset of A is sorted in ascending (DTRDx = 1) or descending
                     76: *>         (DTRDx = -1) order.
                     77: *> \endverbatim
                     78: *>
                     79: *> \param[out] INDEX
                     80: *> \verbatim
                     81: *>          INDEX is INTEGER array, dimension (N1+N2)
                     82: *>         On exit this array will contain a permutation such that
                     83: *>         if B( I ) = A( INDEX( I ) ) for I=1,N1+N2, then B will be
                     84: *>         sorted in ascending order.
                     85: *> \endverbatim
                     86: *
                     87: *  Authors:
                     88: *  ========
                     89: *
                     90: *> \author Univ. of Tennessee 
                     91: *> \author Univ. of California Berkeley 
                     92: *> \author Univ. of Colorado Denver 
                     93: *> \author NAG Ltd. 
                     94: *
                     95: *> \date November 2011
                     96: *
                     97: *> \ingroup auxOTHERcomputational
                     98: *
                     99: *  =====================================================================
1.1       bertrand  100:       SUBROUTINE DLAMRG( N1, N2, A, DTRD1, DTRD2, INDEX )
                    101: *
1.8       bertrand  102: *  -- LAPACK computational routine (version 3.4.0) --
1.1       bertrand  103: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                    104: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.8       bertrand  105: *     November 2011
1.1       bertrand  106: *
                    107: *     .. Scalar Arguments ..
                    108:       INTEGER            DTRD1, DTRD2, N1, N2
                    109: *     ..
                    110: *     .. Array Arguments ..
                    111:       INTEGER            INDEX( * )
                    112:       DOUBLE PRECISION   A( * )
                    113: *     ..
                    114: *
                    115: *  =====================================================================
                    116: *
                    117: *     .. Local Scalars ..
                    118:       INTEGER            I, IND1, IND2, N1SV, N2SV
                    119: *     ..
                    120: *     .. Executable Statements ..
                    121: *
                    122:       N1SV = N1
                    123:       N2SV = N2
                    124:       IF( DTRD1.GT.0 ) THEN
                    125:          IND1 = 1
                    126:       ELSE
                    127:          IND1 = N1
                    128:       END IF
                    129:       IF( DTRD2.GT.0 ) THEN
                    130:          IND2 = 1 + N1
                    131:       ELSE
                    132:          IND2 = N1 + N2
                    133:       END IF
                    134:       I = 1
                    135: *     while ( (N1SV > 0) & (N2SV > 0) )
                    136:    10 CONTINUE
                    137:       IF( N1SV.GT.0 .AND. N2SV.GT.0 ) THEN
                    138:          IF( A( IND1 ).LE.A( IND2 ) ) THEN
                    139:             INDEX( I ) = IND1
                    140:             I = I + 1
                    141:             IND1 = IND1 + DTRD1
                    142:             N1SV = N1SV - 1
                    143:          ELSE
                    144:             INDEX( I ) = IND2
                    145:             I = I + 1
                    146:             IND2 = IND2 + DTRD2
                    147:             N2SV = N2SV - 1
                    148:          END IF
                    149:          GO TO 10
                    150:       END IF
                    151: *     end while
                    152:       IF( N1SV.EQ.0 ) THEN
                    153:          DO 20 N1SV = 1, N2SV
                    154:             INDEX( I ) = IND2
                    155:             I = I + 1
                    156:             IND2 = IND2 + DTRD2
                    157:    20    CONTINUE
                    158:       ELSE
                    159: *     N2SV .EQ. 0
                    160:          DO 30 N2SV = 1, N1SV
                    161:             INDEX( I ) = IND1
                    162:             I = I + 1
                    163:             IND1 = IND1 + DTRD1
                    164:    30    CONTINUE
                    165:       END IF
                    166: *
                    167:       RETURN
                    168: *
                    169: *     End of DLAMRG
                    170: *
                    171:       END