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SUBROUTINE DLAMRG( N1, N2, A, DTRD1, DTRD2, INDEX )
*
* -- LAPACK routine (version 3.1) --
* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
* November 2006
*
* .. Scalar Arguments ..
INTEGER DTRD1, DTRD2, N1, N2
* ..
* .. Array Arguments ..
INTEGER INDEX( * )
DOUBLE PRECISION A( * )
* ..
*
* Purpose
* =======
*
* 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.
*
* Arguments
* =========
*
* N1 (input) INTEGER
* N2 (input) INTEGER
* These arguements contain the respective lengths of the two
* sorted lists to be merged.
*
* A (input) 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.
*
* DTRD1 (input) INTEGER
* DTRD2 (input) 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.
*
* INDEX (output) 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.
*
* =====================================================================
*
* .. 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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