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    1:       SUBROUTINE DLAMRG( N1, N2, A, DTRD1, DTRD2, INDEX )
    2: *
    3: *  -- LAPACK routine (version 3.2) --
    4: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
    5: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
    6: *     November 2006
    7: *
    8: *     .. Scalar Arguments ..
    9:       INTEGER            DTRD1, DTRD2, N1, N2
   10: *     ..
   11: *     .. Array Arguments ..
   12:       INTEGER            INDEX( * )
   13:       DOUBLE PRECISION   A( * )
   14: *     ..
   15: *
   16: *  Purpose
   17: *  =======
   18: *
   19: *  DLAMRG will create a permutation list which will merge the elements
   20: *  of A (which is composed of two independently sorted sets) into a
   21: *  single set which is sorted in ascending order.
   22: *
   23: *  Arguments
   24: *  =========
   25: *
   26: *  N1     (input) INTEGER
   27: *  N2     (input) INTEGER
   28: *         These arguements contain the respective lengths of the two
   29: *         sorted lists to be merged.
   30: *
   31: *  A      (input) DOUBLE PRECISION array, dimension (N1+N2)
   32: *         The first N1 elements of A contain a list of numbers which
   33: *         are sorted in either ascending or descending order.  Likewise
   34: *         for the final N2 elements.
   35: *
   36: *  DTRD1  (input) INTEGER
   37: *  DTRD2  (input) INTEGER
   38: *         These are the strides to be taken through the array A.
   39: *         Allowable strides are 1 and -1.  They indicate whether a
   40: *         subset of A is sorted in ascending (DTRDx = 1) or descending
   41: *         (DTRDx = -1) order.
   42: *
   43: *  INDEX  (output) INTEGER array, dimension (N1+N2)
   44: *         On exit this array will contain a permutation such that
   45: *         if B( I ) = A( INDEX( I ) ) for I=1,N1+N2, then B will be
   46: *         sorted in ascending order.
   47: *
   48: *  =====================================================================
   49: *
   50: *     .. Local Scalars ..
   51:       INTEGER            I, IND1, IND2, N1SV, N2SV
   52: *     ..
   53: *     .. Executable Statements ..
   54: *
   55:       N1SV = N1
   56:       N2SV = N2
   57:       IF( DTRD1.GT.0 ) THEN
   58:          IND1 = 1
   59:       ELSE
   60:          IND1 = N1
   61:       END IF
   62:       IF( DTRD2.GT.0 ) THEN
   63:          IND2 = 1 + N1
   64:       ELSE
   65:          IND2 = N1 + N2
   66:       END IF
   67:       I = 1
   68: *     while ( (N1SV > 0) & (N2SV > 0) )
   69:    10 CONTINUE
   70:       IF( N1SV.GT.0 .AND. N2SV.GT.0 ) THEN
   71:          IF( A( IND1 ).LE.A( IND2 ) ) THEN
   72:             INDEX( I ) = IND1
   73:             I = I + 1
   74:             IND1 = IND1 + DTRD1
   75:             N1SV = N1SV - 1
   76:          ELSE
   77:             INDEX( I ) = IND2
   78:             I = I + 1
   79:             IND2 = IND2 + DTRD2
   80:             N2SV = N2SV - 1
   81:          END IF
   82:          GO TO 10
   83:       END IF
   84: *     end while
   85:       IF( N1SV.EQ.0 ) THEN
   86:          DO 20 N1SV = 1, N2SV
   87:             INDEX( I ) = IND2
   88:             I = I + 1
   89:             IND2 = IND2 + DTRD2
   90:    20    CONTINUE
   91:       ELSE
   92: *     N2SV .EQ. 0
   93:          DO 30 N2SV = 1, N1SV
   94:             INDEX( I ) = IND1
   95:             I = I + 1
   96:             IND1 = IND1 + DTRD1
   97:    30    CONTINUE
   98:       END IF
   99: *
  100:       RETURN
  101: *
  102: *     End of DLAMRG
  103: *
  104:       END