LAPACK 3.11.0 LAPACK: Linear Algebra PACKage
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dlamrg.f
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1*> \brief \b DLAMRG creates a permutation list to merge the entries of two independently sorted sets into a single set sorted in ascending order.
2*
3* =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6* http://www.netlib.org/lapack/explore-html/
7*
8*> \htmlonly
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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 arguments 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*> \ingroup auxOTHERcomputational
96*
97* =====================================================================
98 SUBROUTINE dlamrg( N1, N2, A, DTRD1, DTRD2, INDEX )
99*
100* -- LAPACK computational routine --
101* -- LAPACK is a software package provided by Univ. of Tennessee, --
102* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
103*
104* .. Scalar Arguments ..
105 INTEGER DTRD1, DTRD2, N1, N2
106* ..
107* .. Array Arguments ..
108 INTEGER INDEX( * )
109 DOUBLE PRECISION A( * )
110* ..
111*
112* =====================================================================
113*
114* .. Local Scalars ..
115 INTEGER I, IND1, IND2, N1SV, N2SV
116* ..
117* .. Executable Statements ..
118*
119 n1sv = n1
120 n2sv = n2
121 IF( dtrd1.GT.0 ) THEN
122 ind1 = 1
123 ELSE
124 ind1 = n1
125 END IF
126 IF( dtrd2.GT.0 ) THEN
127 ind2 = 1 + n1
128 ELSE
129 ind2 = n1 + n2
130 END IF
131 i = 1
132* while ( (N1SV > 0) & (N2SV > 0) )
133 10 CONTINUE
134 IF( n1sv.GT.0 .AND. n2sv.GT.0 ) THEN
135 IF( a( ind1 ).LE.a( ind2 ) ) THEN
136 index( i ) = ind1
137 i = i + 1
138 ind1 = ind1 + dtrd1
139 n1sv = n1sv - 1
140 ELSE
141 index( i ) = ind2
142 i = i + 1
143 ind2 = ind2 + dtrd2
144 n2sv = n2sv - 1
145 END IF
146 GO TO 10
147 END IF
148* end while
149 IF( n1sv.EQ.0 ) THEN
150 DO 20 n1sv = 1, n2sv
151 index( i ) = ind2
152 i = i + 1
153 ind2 = ind2 + dtrd2
154 20 CONTINUE
155 ELSE
156* N2SV .EQ. 0
157 DO 30 n2sv = 1, n1sv
158 index( i ) = ind1
159 i = i + 1
160 ind1 = ind1 + dtrd1
161 30 CONTINUE
162 END IF
163*
164 RETURN
165*
166* End of DLAMRG
167*
168 END
subroutine dlamrg(N1, N2, A, DTRD1, DTRD2, INDEX)
DLAMRG creates a permutation list to merge the entries of two independently sorted sets into a single...
Definition: dlamrg.f:99