Annotation of rpl/lapack/lapack/dsyswapr.f, revision 1.10
1.7 bertrand 1: *> \brief \b DSYSWAPR applies an elementary permutation on the rows and columns of a symmetric matrix.
1.4 bertrand 2: *
3: * =========== DOCUMENTATION ===========
4: *
5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
7: *
8: *> \htmlonly
9: *> Download DSYSWAPR + dependencies
10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dsyswapr.f">
11: *> [TGZ]</a>
12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dsyswapr.f">
13: *> [ZIP]</a>
14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dsyswapr.f">
15: *> [TXT]</a>
16: *> \endhtmlonly
17: *
18: * Definition:
19: * ===========
20: *
21: * SUBROUTINE DSYSWAPR( UPLO, N, A, LDA, I1, I2)
22: *
23: * .. Scalar Arguments ..
24: * CHARACTER UPLO
25: * INTEGER I1, I2, LDA, N
26: * ..
27: * .. Array Arguments ..
28: * DOUBLE PRECISION A( LDA, N )
29: *
30: *
31: *> \par Purpose:
32: * =============
33: *>
34: *> \verbatim
35: *>
36: *> DSYSWAPR applies an elementary permutation on the rows and the columns of
37: *> a symmetric matrix.
38: *> \endverbatim
39: *
40: * Arguments:
41: * ==========
42: *
43: *> \param[in] UPLO
44: *> \verbatim
45: *> UPLO is CHARACTER*1
46: *> Specifies whether the details of the factorization are stored
47: *> as an upper or lower triangular matrix.
48: *> = 'U': Upper triangular, form is A = U*D*U**T;
49: *> = 'L': Lower triangular, form is A = L*D*L**T.
50: *> \endverbatim
51: *>
52: *> \param[in] N
53: *> \verbatim
54: *> N is INTEGER
55: *> The order of the matrix A. N >= 0.
56: *> \endverbatim
57: *>
58: *> \param[in,out] A
59: *> \verbatim
60: *> A is DOUBLE PRECISION array, dimension (LDA,N)
61: *> On entry, the NB diagonal matrix D and the multipliers
62: *> used to obtain the factor U or L as computed by DSYTRF.
63: *>
64: *> On exit, if INFO = 0, the (symmetric) inverse of the original
65: *> matrix. If UPLO = 'U', the upper triangular part of the
66: *> inverse is formed and the part of A below the diagonal is not
67: *> referenced; if UPLO = 'L' the lower triangular part of the
68: *> inverse is formed and the part of A above the diagonal is
69: *> not referenced.
70: *> \endverbatim
71: *>
72: *> \param[in] LDA
73: *> \verbatim
74: *> LDA is INTEGER
75: *> The leading dimension of the array A. LDA >= max(1,N).
76: *> \endverbatim
77: *>
78: *> \param[in] I1
79: *> \verbatim
80: *> I1 is INTEGER
81: *> Index of the first row to swap
82: *> \endverbatim
83: *>
84: *> \param[in] I2
85: *> \verbatim
86: *> I2 is INTEGER
87: *> Index of the second row to swap
88: *> \endverbatim
89: *
90: * Authors:
91: * ========
92: *
93: *> \author Univ. of Tennessee
94: *> \author Univ. of California Berkeley
95: *> \author Univ. of Colorado Denver
96: *> \author NAG Ltd.
97: *
1.7 bertrand 98: *> \date September 2012
1.4 bertrand 99: *
100: *> \ingroup doubleSYauxiliary
101: *
102: * =====================================================================
1.3 bertrand 103: SUBROUTINE DSYSWAPR( UPLO, N, A, LDA, I1, I2)
1.1 bertrand 104: *
1.7 bertrand 105: * -- LAPACK auxiliary routine (version 3.4.2) --
1.1 bertrand 106: * -- LAPACK is a software package provided by Univ. of Tennessee, --
107: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.7 bertrand 108: * September 2012
1.1 bertrand 109: *
110: * .. Scalar Arguments ..
111: CHARACTER UPLO
1.3 bertrand 112: INTEGER I1, I2, LDA, N
1.1 bertrand 113: * ..
114: * .. Array Arguments ..
1.3 bertrand 115: DOUBLE PRECISION A( LDA, N )
1.1 bertrand 116: *
117: * =====================================================================
118: *
119: * ..
120: * .. Local Scalars ..
121: LOGICAL UPPER
122: INTEGER I
123: DOUBLE PRECISION TMP
124: *
125: * .. External Functions ..
126: LOGICAL LSAME
127: EXTERNAL LSAME
128: * ..
129: * .. External Subroutines ..
130: EXTERNAL DSWAP
131: * ..
132: * .. Executable Statements ..
133: *
134: UPPER = LSAME( UPLO, 'U' )
135: IF (UPPER) THEN
136: *
137: * UPPER
138: * first swap
139: * - swap column I1 and I2 from I1 to I1-1
140: CALL DSWAP( I1-1, A(1,I1), 1, A(1,I2), 1 )
141: *
142: * second swap :
143: * - swap A(I1,I1) and A(I2,I2)
144: * - swap row I1 from I1+1 to I2-1 with col I2 from I1+1 to I2-1
145: TMP=A(I1,I1)
146: A(I1,I1)=A(I2,I2)
147: A(I2,I2)=TMP
148: *
149: DO I=1,I2-I1-1
150: TMP=A(I1,I1+I)
151: A(I1,I1+I)=A(I1+I,I2)
152: A(I1+I,I2)=TMP
153: END DO
154: *
155: * third swap
156: * - swap row I1 and I2 from I2+1 to N
157: DO I=I2+1,N
158: TMP=A(I1,I)
159: A(I1,I)=A(I2,I)
160: A(I2,I)=TMP
161: END DO
162: *
163: ELSE
164: *
165: * LOWER
166: * first swap
167: * - swap row I1 and I2 from I1 to I1-1
1.3 bertrand 168: CALL DSWAP( I1-1, A(I1,1), LDA, A(I2,1), LDA )
1.1 bertrand 169: *
170: * second swap :
171: * - swap A(I1,I1) and A(I2,I2)
172: * - swap col I1 from I1+1 to I2-1 with row I2 from I1+1 to I2-1
173: TMP=A(I1,I1)
174: A(I1,I1)=A(I2,I2)
175: A(I2,I2)=TMP
176: *
177: DO I=1,I2-I1-1
178: TMP=A(I1+I,I1)
179: A(I1+I,I1)=A(I2,I1+I)
180: A(I2,I1+I)=TMP
181: END DO
182: *
183: * third swap
184: * - swap col I1 and I2 from I2+1 to N
185: DO I=I2+1,N
186: TMP=A(I,I1)
187: A(I,I1)=A(I,I2)
188: A(I,I2)=TMP
189: END DO
190: *
191: ENDIF
192: END SUBROUTINE DSYSWAPR
193:
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