LAPACK  3.10.0
LAPACK: Linear Algebra PACKage
dlaswp.f
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1 *> \brief \b DLASWP performs a series of row interchanges on a general rectangular matrix.
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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15 *> [TXT]</a>
16 *> \endhtmlonly
17 *
18 * Definition:
19 * ===========
20 *
21 * SUBROUTINE DLASWP( N, A, LDA, K1, K2, IPIV, INCX )
22 *
23 * .. Scalar Arguments ..
24 * INTEGER INCX, K1, K2, LDA, N
25 * ..
26 * .. Array Arguments ..
27 * INTEGER IPIV( * )
28 * DOUBLE PRECISION A( LDA, * )
29 * ..
30 *
31 *
32 *> \par Purpose:
33 * =============
34 *>
35 *> \verbatim
36 *>
37 *> DLASWP performs a series of row interchanges on the matrix A.
38 *> One row interchange is initiated for each of rows K1 through K2 of A.
39 *> \endverbatim
40 *
41 * Arguments:
42 * ==========
43 *
44 *> \param[in] N
45 *> \verbatim
46 *> N is INTEGER
47 *> The number of columns of the matrix A.
48 *> \endverbatim
49 *>
50 *> \param[in,out] A
51 *> \verbatim
52 *> A is DOUBLE PRECISION array, dimension (LDA,N)
53 *> On entry, the matrix of column dimension N to which the row
54 *> interchanges will be applied.
55 *> On exit, the permuted matrix.
56 *> \endverbatim
57 *>
58 *> \param[in] LDA
59 *> \verbatim
60 *> LDA is INTEGER
61 *> The leading dimension of the array A.
62 *> \endverbatim
63 *>
64 *> \param[in] K1
65 *> \verbatim
66 *> K1 is INTEGER
67 *> The first element of IPIV for which a row interchange will
68 *> be done.
69 *> \endverbatim
70 *>
71 *> \param[in] K2
72 *> \verbatim
73 *> K2 is INTEGER
74 *> (K2-K1+1) is the number of elements of IPIV for which a row
75 *> interchange will be done.
76 *> \endverbatim
77 *>
78 *> \param[in] IPIV
79 *> \verbatim
80 *> IPIV is INTEGER array, dimension (K1+(K2-K1)*abs(INCX))
81 *> The vector of pivot indices. Only the elements in positions
82 *> K1 through K1+(K2-K1)*abs(INCX) of IPIV are accessed.
83 *> IPIV(K1+(K-K1)*abs(INCX)) = L implies rows K and L are to be
84 *> interchanged.
85 *> \endverbatim
86 *>
87 *> \param[in] INCX
88 *> \verbatim
89 *> INCX is INTEGER
90 *> The increment between successive values of IPIV. If INCX
91 *> is negative, the pivots are applied in reverse order.
92 *> \endverbatim
93 *
94 * Authors:
95 * ========
96 *
97 *> \author Univ. of Tennessee
98 *> \author Univ. of California Berkeley
99 *> \author Univ. of Colorado Denver
100 *> \author NAG Ltd.
101 *
102 *> \ingroup doubleOTHERauxiliary
103 *
104 *> \par Further Details:
105 * =====================
106 *>
107 *> \verbatim
108 *>
109 *> Modified by
110 *> R. C. Whaley, Computer Science Dept., Univ. of Tenn., Knoxville, USA
111 *> \endverbatim
112 *>
113 * =====================================================================
114  SUBROUTINE dlaswp( N, A, LDA, K1, K2, IPIV, INCX )
115 *
116 * -- LAPACK auxiliary routine --
117 * -- LAPACK is a software package provided by Univ. of Tennessee, --
118 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
119 *
120 * .. Scalar Arguments ..
121  INTEGER INCX, K1, K2, LDA, N
122 * ..
123 * .. Array Arguments ..
124  INTEGER IPIV( * )
125  DOUBLE PRECISION A( LDA, * )
126 * ..
127 *
128 * =====================================================================
129 *
130 * .. Local Scalars ..
131  INTEGER I, I1, I2, INC, IP, IX, IX0, J, K, N32
132  DOUBLE PRECISION TEMP
133 * ..
134 * .. Executable Statements ..
135 *
136 * Interchange row I with row IPIV(K1+(I-K1)*abs(INCX)) for each of rows
137 * K1 through K2.
138 *
139  IF( incx.GT.0 ) THEN
140  ix0 = k1
141  i1 = k1
142  i2 = k2
143  inc = 1
144  ELSE IF( incx.LT.0 ) THEN
145  ix0 = k1 + ( k1-k2 )*incx
146  i1 = k2
147  i2 = k1
148  inc = -1
149  ELSE
150  RETURN
151  END IF
152 *
153  n32 = ( n / 32 )*32
154  IF( n32.NE.0 ) THEN
155  DO 30 j = 1, n32, 32
156  ix = ix0
157  DO 20 i = i1, i2, inc
158  ip = ipiv( ix )
159  IF( ip.NE.i ) THEN
160  DO 10 k = j, j + 31
161  temp = a( i, k )
162  a( i, k ) = a( ip, k )
163  a( ip, k ) = temp
164  10 CONTINUE
165  END IF
166  ix = ix + incx
167  20 CONTINUE
168  30 CONTINUE
169  END IF
170  IF( n32.NE.n ) THEN
171  n32 = n32 + 1
172  ix = ix0
173  DO 50 i = i1, i2, inc
174  ip = ipiv( ix )
175  IF( ip.NE.i ) THEN
176  DO 40 k = n32, n
177  temp = a( i, k )
178  a( i, k ) = a( ip, k )
179  a( ip, k ) = temp
180  40 CONTINUE
181  END IF
182  ix = ix + incx
183  50 CONTINUE
184  END IF
185 *
186  RETURN
187 *
188 * End of DLASWP
189 *
190  END
subroutine dlaswp(N, A, LDA, K1, K2, IPIV, INCX)
DLASWP performs a series of row interchanges on a general rectangular matrix.
Definition: dlaswp.f:115