Return to ztrttp.f CVS log

Up to [local] / rpl / lapack / lapack

Annotation of rpl/lapack/lapack/ztrttp.f, revision 1.3

1.1       bertrand    1:       SUBROUTINE ZTRTTP( UPLO, N, A, LDA, AP, INFO )
                      2: *
                      3: *  -- LAPACK routine (version 3.2) --
                      4: *
                      5: *  -- Contributed by Fred Gustavson of the IBM Watson Research Center --
                      6: *  --            and Julien Langou of the Univ. of Colorado Denver    --
                      7: *  -- November 2008                                                   --
                      8: *
                      9: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                     10: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
                     11: *
                     12: *     .. Scalar Arguments ..
                     13:       CHARACTER          UPLO
                     14:       INTEGER            INFO, N, LDA
                     15: *     ..
                     16: *     .. Array Arguments ..
                     17:       COMPLEX*16         A( LDA, * ), AP( * )
                     18: *     ..
                     19: *
                     20: *  Purpose
                     21: *  =======
                     22: *
                     23: *  ZTRTTP copies a triangular matrix A from full format (TR) to standard
                     24: *  packed format (TP).
                     25: *
                     26: *  Arguments
                     27: *  =========
                     28: *
                     29: *  UPLO    (input) CHARACTER
                     30: *          = 'U':  A is upper triangular;
                     31: *          = 'L':  A is lower triangular.
                     32: *
                     33: *  N       (input) INTEGER
                     34: *          The order of the matrices AP and A.  N >= 0.
                     35: *
                     36: *  A       (input) COMPLEX*16 array, dimension (LDA,N)
                     37: *          On entry, the triangular matrix A.  If UPLO = 'U', the leading
                     38: *          N-by-N upper triangular part of A contains the upper
                     39: *          triangular part of the matrix A, and the strictly lower
                     40: *          triangular part of A is not referenced.  If UPLO = 'L', the
                     41: *          leading N-by-N lower triangular part of A contains the lower
                     42: *          triangular part of the matrix A, and the strictly upper
                     43: *          triangular part of A is not referenced.
                     44: *
                     45: *  LDA     (input) INTEGER
                     46: *          The leading dimension of the array A.  LDA >= max(1,N).
                     47: *
                     48: *  AP      (output) COMPLEX*16 array, dimension ( N*(N+1)/2 ),
                     49: *          On exit, the upper or lower triangular matrix A, packed
                     50: *          columnwise in a linear array. The j-th column of A is stored
                     51: *          in the array AP as follows:
                     52: *          if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
                     53: *          if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.
                     54: *
                     55: *  INFO    (output) INTEGER
                     56: *          = 0:  successful exit
                     57: *          < 0:  if INFO = -i, the i-th argument had an illegal value
                     58: *
                     59: *  =====================================================================
                     60: *
                     61: *     .. Parameters ..
                     62: *     ..
                     63: *     .. Local Scalars ..
                     64:       LOGICAL            LOWER
                     65:       INTEGER            I, J, K
                     66: *     ..
                     67: *     .. External Functions ..
                     68:       LOGICAL            LSAME
                     69:       EXTERNAL           LSAME
                     70: *     ..
                     71: *     .. External Subroutines ..
                     72:       EXTERNAL           XERBLA
                     73: *     ..
                     74: *     .. Executable Statements ..
                     75: *
                     76: *     Test the input parameters.
                     77: *
                     78:       INFO = 0
                     79:       LOWER = LSAME( UPLO, 'L' )
                     80:       IF( .NOT.LOWER .AND. .NOT.LSAME( UPLO, 'U' ) ) THEN
                     81:          INFO = -1
                     82:       ELSE IF( N.LT.0 ) THEN
                     83:          INFO = -2
                     84:       ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
                     85:          INFO = -4
                     86:       END IF
                     87:       IF( INFO.NE.0 ) THEN
                     88:          CALL XERBLA( 'ZTRTTP', -INFO )
                     89:          RETURN
                     90:       END IF
                     91: *
                     92:       IF( LOWER ) THEN
                     93:          K = 0
                     94:          DO J = 1, N
                     95:             DO I = J, N
                     96:                K = K + 1
                     97:                AP( K ) = A( I, J )
                     98:             END DO
                     99:          END DO
                    100:       ELSE
                    101:          K = 0
                    102:          DO J = 1, N
                    103:             DO I = 1, J
                    104:                K = K + 1
                    105:                AP( K ) = A( I, J )
                    106:             END DO
                    107:          END DO
                    108:       END IF
                    109: *
                    110: *
                    111:       RETURN
                    112: *
                    113: *     End of ZTRTTP
                    114: *
                    115:       END