LAPACK 3.12.0
LAPACK: Linear Algebra PACKage
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◆ ctrttp()

subroutine ctrttp ( character  uplo,
integer  n,
complex, dimension( lda, * )  a,
integer  lda,
complex, dimension( * )  ap,
integer  info 
)

CTRTTP copies a triangular matrix from the standard full format (TR) to the standard packed format (TP).

Download CTRTTP + dependencies [TGZ] [ZIP] [TXT]

Purpose:
 CTRTTP copies a triangular matrix A from full format (TR) to standard
 packed format (TP).
Parameters
[in]UPLO
          UPLO is CHARACTER*1
          = 'U':  A is upper triangular;
          = 'L':  A is lower triangular.
[in]N
          N is INTEGER
          The order of the matrices AP and A.  N >= 0.
[in]A
          A is COMPLEX array, dimension (LDA,N)
          On entry, the triangular matrix A.  If UPLO = 'U', the leading
          N-by-N upper triangular part of A contains the upper
          triangular part of the matrix A, and the strictly lower
          triangular part of A is not referenced.  If UPLO = 'L', the
          leading N-by-N lower triangular part of A contains the lower
          triangular part of the matrix A, and the strictly upper
          triangular part of A is not referenced.
[in]LDA
          LDA is INTEGER
          The leading dimension of the array A.  LDA >= max(1,N).
[out]AP
          AP is COMPLEX array, dimension ( N*(N+1)/2 ),
          On exit, the upper or lower triangular matrix A, packed
          columnwise in a linear array. The j-th column of A is stored
          in the array AP as follows:
          if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
          if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.
[out]INFO
          INFO is INTEGER
          = 0:  successful exit
          < 0:  if INFO = -i, the i-th argument had an illegal value
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.

Definition at line 103 of file ctrttp.f.

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 COMPLEX 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( 'CTRTTP', -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 CTRTTP
172*
subroutine xerbla(srname, info)
Definition cblat2.f:3285
logical function lsame(ca, cb)
LSAME
Definition lsame.f:48
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