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Annotation of rpl/lapack/lapack/dtpttr.f, revision 1.4

1.1       bertrand    1:       SUBROUTINE DTPTTR( UPLO, N, AP, A, LDA, INFO )
                      2: *
1.4     ! bertrand    3: *  -- LAPACK routine (version 3.3.0)                                    --
1.1       bertrand    4: *
                      5: *  -- Contributed by Julien Langou of the Univ. of Colorado Denver    --
1.4     ! bertrand    6: *     November 2010                                                   --
1.1       bertrand    7: *
                      8: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                      9: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
                     10: *
                     11: *     .. Scalar Arguments ..
                     12:       CHARACTER          UPLO
                     13:       INTEGER            INFO, N, LDA
                     14: *     ..
                     15: *     .. Array Arguments ..
                     16:       DOUBLE PRECISION   A( LDA, * ), AP( * )
                     17: *     ..
                     18: *
                     19: *  Purpose
                     20: *  =======
                     21: *
                     22: *  DTPTTR copies a triangular matrix A from standard packed format (TP)
                     23: *  to standard full format (TR).
                     24: *
                     25: *  Arguments
                     26: *  =========
                     27: *
1.4     ! bertrand   28: *  UPLO    (input) CHARACTER*1
1.1       bertrand   29: *          = 'U':  A is upper triangular.
                     30: *          = 'L':  A is lower triangular.
                     31: *
                     32: *  N       (input) INTEGER
                     33: *          The order of the matrix A. N >= 0.
                     34: *
                     35: *  AP      (input) DOUBLE PRECISION array, dimension ( N*(N+1)/2 ),
                     36: *          On entry, the upper or lower triangular matrix A, packed
                     37: *          columnwise in a linear array. The j-th column of A is stored
                     38: *          in the array AP as follows:
                     39: *          if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
                     40: *          if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.
                     41: *
                     42: *  A       (output) DOUBLE PRECISION array, dimension ( LDA, N )
                     43: *          On exit, the triangular matrix A.  If UPLO = 'U', the leading
                     44: *          N-by-N upper triangular part of A contains the upper
                     45: *          triangular part of the matrix A, and the strictly lower
                     46: *          triangular part of A is not referenced.  If UPLO = 'L', the
                     47: *          leading N-by-N lower triangular part of A contains the lower
                     48: *          triangular part of the matrix A, and the strictly upper
                     49: *          triangular part of A is not referenced.
                     50: *
                     51: *  LDA     (input) INTEGER
                     52: *          The leading dimension of the array A.  LDA >= max(1,N).
                     53: *
                     54: *  INFO    (output) INTEGER
                     55: *          = 0:  successful exit
                     56: *          < 0:  if INFO = -i, the i-th argument had an illegal value
                     57: *
                     58: *  =====================================================================
                     59: *
                     60: *     .. Parameters ..
                     61: *     ..
                     62: *     .. Local Scalars ..
                     63:       LOGICAL            LOWER
                     64:       INTEGER            I, J, K
                     65: *     ..
                     66: *     .. External Functions ..
                     67:       LOGICAL            LSAME
                     68:       EXTERNAL           LSAME
                     69: *     ..
                     70: *     .. External Subroutines ..
                     71:       EXTERNAL           XERBLA
                     72: *     ..
                     73: *     .. Executable Statements ..
                     74: *
                     75: *     Test the input parameters.
                     76: *
                     77:       INFO = 0
                     78:       LOWER = LSAME( UPLO, 'L' )
                     79:       IF( .NOT.LOWER .AND. .NOT.LSAME( UPLO, 'U' ) ) THEN
                     80:          INFO = -1
                     81:       ELSE IF( N.LT.0 ) THEN
                     82:          INFO = -2
                     83:       ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
                     84:          INFO = -5
                     85:       END IF
                     86:       IF( INFO.NE.0 ) THEN
                     87:          CALL XERBLA( 'DTPTTR', -INFO )
                     88:          RETURN
                     89:       END IF
                     90: *
                     91:       IF( LOWER ) THEN
                     92:          K = 0
                     93:          DO J = 1, N
                     94:             DO I = J, N
                     95:                K = K + 1
                     96:                A( I, J ) = AP( K )
                     97:             END DO
                     98:          END DO
                     99:       ELSE
                    100:          K = 0
                    101:          DO J = 1, N
                    102:             DO I = 1, J
                    103:                K = K + 1
                    104:                A( I, J ) = AP( K )
                    105:             END DO
                    106:          END DO
                    107:       END IF
                    108: *
                    109: *
                    110:       RETURN
                    111: *
                    112: *     End of DTPTTR
                    113: *
                    114:       END