LAPACK 3.11.0 LAPACK: Linear Algebra PACKage
Searching...
No Matches

## ◆ dlamrg()

 subroutine dlamrg ( integer N1, integer N2, double precision, dimension( * ) A, integer DTRD1, integer DTRD2, integer, dimension( * ) INDEX )

DLAMRG creates a permutation list to merge the entries of two independently sorted sets into a single set sorted in ascending order.

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.```
Parameters
 [in] N1 ` N1 is INTEGER` [in] N2 ``` N2 is INTEGER These arguments contain the respective lengths of the two sorted lists to be merged.``` [in] A ``` A is 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.``` [in] DTRD1 ` DTRD1 is INTEGER` [in] DTRD2 ``` DTRD2 is 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.``` [out] INDEX ``` INDEX is 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.```

Definition at line 98 of file dlamrg.f.

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*
Here is the caller graph for this function: