 LAPACK  3.10.1 LAPACK: Linear Algebra PACKage

## ◆ strttp()

 subroutine strttp ( character UPLO, integer N, real, dimension( lda, * ) A, integer LDA, real, dimension( * ) AP, integer INFO )

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

Purpose:
``` STRTTP 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 REAL array, dimension (LDA,N) On exit, 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 REAL 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```

Definition at line 103 of file strttp.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  REAL 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( 'STRTTP', -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  RETURN
169 *
170 * End of STRTTP
171 *
subroutine xerbla(SRNAME, INFO)
XERBLA
Definition: xerbla.f:60
logical function lsame(CA, CB)
LSAME
Definition: lsame.f:53
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