LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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dtrttp.f
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1*> \brief \b DTRTTP copies a triangular matrix from the standard full format (TR) to the standard packed format (TP).
2*
3* =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6* http://www.netlib.org/lapack/explore-html/
7*
8*> \htmlonly
9*> Download DTRTTP + dependencies
10*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dtrttp.f">
11*> [TGZ]</a>
12*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dtrttp.f">
13*> [ZIP]</a>
14*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dtrttp.f">
15*> [TXT]</a>
16*> \endhtmlonly
17*
18* Definition:
19* ===========
20*
21* SUBROUTINE DTRTTP( UPLO, N, A, LDA, AP, INFO )
22*
23* .. Scalar Arguments ..
24* CHARACTER UPLO
25* INTEGER INFO, N, LDA
26* ..
27* .. Array Arguments ..
28* DOUBLE PRECISION A( LDA, * ), AP( * )
29* ..
30*
31*
32*> \par Purpose:
33* =============
34*>
35*> \verbatim
36*>
37*> DTRTTP copies a triangular matrix A from full format (TR) to standard
38*> packed format (TP).
39*> \endverbatim
40*
41* Arguments:
42* ==========
43*
44*> \param[in] UPLO
45*> \verbatim
46*> UPLO is CHARACTER*1
47*> = 'U': A is upper triangular.
48*> = 'L': A is lower triangular.
49*> \endverbatim
50*>
51*> \param[in] N
52*> \verbatim
53*> N is INTEGER
54*> The order of the matrices AP and A. N >= 0.
55*> \endverbatim
56*>
57*> \param[in] A
58*> \verbatim
59*> A is DOUBLE PRECISION array, dimension (LDA,N)
60*> On exit, the triangular matrix A. If UPLO = 'U', the leading
61*> N-by-N upper triangular part of A contains the upper
62*> triangular part of the matrix A, and the strictly lower
63*> triangular part of A is not referenced. If UPLO = 'L', the
64*> leading N-by-N lower triangular part of A contains the lower
65*> triangular part of the matrix A, and the strictly upper
66*> triangular part of A is not referenced.
67*> \endverbatim
68*>
69*> \param[in] LDA
70*> \verbatim
71*> LDA is INTEGER
72*> The leading dimension of the array A. LDA >= max(1,N).
73*> \endverbatim
74*>
75*> \param[out] AP
76*> \verbatim
77*> AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)
78*> On exit, the upper or lower triangular matrix A, packed
79*> columnwise in a linear array. The j-th column of A is stored
80*> in the array AP as follows:
81*> if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
82*> if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.
83*> \endverbatim
84*>
85*> \param[out] INFO
86*> \verbatim
87*> INFO is INTEGER
88*> = 0: successful exit
89*> < 0: if INFO = -i, the i-th argument had an illegal value
90*> \endverbatim
91*
92* Authors:
93* ========
94*
95*> \author Univ. of Tennessee
96*> \author Univ. of California Berkeley
97*> \author Univ. of Colorado Denver
98*> \author NAG Ltd.
99*
100*> \ingroup doubleOTHERcomputational
101*
102* =====================================================================
103 SUBROUTINE dtrttp( UPLO, N, A, LDA, AP, INFO )
104*
105* -- LAPACK computational routine --
106* -- LAPACK is a software package provided by Univ. of Tennessee, --
107* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
108*
109* .. Scalar Arguments ..
110 CHARACTER UPLO
111 INTEGER INFO, N, LDA
112* ..
113* .. Array Arguments ..
114 DOUBLE PRECISION A( LDA, * ), AP( * )
115* ..
116*
117* =====================================================================
118*
119* .. Parameters ..
120* ..
121* .. Local Scalars ..
122 LOGICAL LOWER
123 INTEGER I, J, K
124* ..
125* .. External Functions ..
126 LOGICAL LSAME
127 EXTERNAL lsame
128* ..
129* .. External Subroutines ..
130 EXTERNAL xerbla
131* ..
132* .. Executable Statements ..
133*
134* Test the input parameters.
135*
136 info = 0
137 lower = lsame( uplo, 'L' )
138 IF( .NOT.lower .AND. .NOT.lsame( uplo, 'U' ) ) THEN
139 info = -1
140 ELSE IF( n.LT.0 ) THEN
141 info = -2
142 ELSE IF( lda.LT.max( 1, n ) ) THEN
143 info = -4
144 END IF
145 IF( info.NE.0 ) THEN
146 CALL xerbla( 'DTRTTP', -info )
147 RETURN
148 END IF
149*
150 IF( lower ) THEN
151 k = 0
152 DO j = 1, n
153 DO i = j, n
154 k = k + 1
155 ap( k ) = a( i, j )
156 END DO
157 END DO
158 ELSE
159 k = 0
160 DO j = 1, n
161 DO i = 1, j
162 k = k + 1
163 ap( k ) = a( i, j )
164 END DO
165 END DO
166 END IF
167*
168*
169 RETURN
170*
171* End of DTRTTP
172*
173 END
subroutine xerbla(SRNAME, INFO)
XERBLA
Definition: xerbla.f:60
subroutine dtrttp(UPLO, N, A, LDA, AP, INFO)
DTRTTP copies a triangular matrix from the standard full format (TR) to the standard packed format (T...
Definition: dtrttp.f:104