TESTING/LIN/dlavsy.f(3)

NAME
TESTING/LIN/dlavsy.f

SYNOPSIS

  Functions/Subroutines
subroutine dlavsy (uplo, trans, diag, n, nrhs, a, lda, ipiv, b, ldb, info)
DLAVSY

Function/Subroutine Documentation

  subroutine dlavsy (character uplo, character trans, character diag, integer n, integer nrhs, double precision, dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, double precision, dimension( ldb, * ) b, integer ldb, integer info)

DLAVSY

Purpose:

    !>
    !> DLAVSY  performs one of the matrix-vector operations
    !>    x := A*x  or  x := A'*x,
    !> where x is an N element vector and A is one of the factors
    !> from the block U*D*U' or L*D*L' factorization computed by DSYTRF.
    !>
    !> If TRANS = 'N', multiplies by U  or U * D  (or L  or L * D)
    !> If TRANS = 'T', multiplies by U' or D * U' (or L' or D * L')
    !> If TRANS = 'C', multiplies by U' or D * U' (or L' or D * L')
    !>

Parameters
    UPLO

    !>          UPLO is CHARACTER*1
    !>          Specifies whether the factor stored in A is upper or lower
    !>          triangular.
    !>          = 'U':  Upper triangular
    !>          = 'L':  Lower triangular
    !>

    TRANS

    !>          TRANS is CHARACTER*1
    !>          Specifies the operation to be performed:
    !>          = 'N':  x := A*x
    !>          = 'T':  x := A'*x
    !>          = 'C':  x := A'*x
    !>

    DIAG

    !>          DIAG is CHARACTER*1
    !>          Specifies whether or not the diagonal blocks are unit
    !>          matrices.  If the diagonal blocks are assumed to be unit,
    !>          then A = U or A = L, otherwise A = U*D or A = L*D.
    !>          = 'U':  Diagonal blocks are assumed to be unit matrices.
    !>          = 'N':  Diagonal blocks are assumed to be non-unit matrices.
    !>

    N

    !>          N is INTEGER
    !>          The number of rows and columns of the matrix A.  N >= 0.
    !>

    NRHS

    !>          NRHS is INTEGER
    !>          The number of right hand sides, i.e., the number of vectors
    !>          x to be multiplied by A.  NRHS >= 0.
    !>

    A

    !>          A is DOUBLE PRECISION array, dimension (LDA,N)
    !>          The block diagonal matrix D and the multipliers used to
    !>          obtain the factor U or L as computed by DSYTRF.
    !>          Stored as a 2-D triangular matrix.
    !>

    LDA

    !>          LDA is INTEGER
    !>          The leading dimension of the array A.  LDA >= max(1,N).
    !>

    IPIV

    !>          IPIV is INTEGER array, dimension (N)
    !>          Details of the interchanges and the block structure of D,
    !>          as determined by DSYTRF.
    !>
    !>          If UPLO = 'U':
    !>               If IPIV(k) > 0, then rows and columns k and IPIV(k)
    !>               were interchanged and D(k,k) is a 1-by-1 diagonal block.
    !>               (If IPIV( k ) = k, no interchange was done).
    !>
    !>               If IPIV(k) = IPIV(k-1) < 0, then rows and
    !>               columns k-1 and -IPIV(k) were interchanged,
    !>               D(k-1:k,k-1:k) is a 2-by-2 diagonal block.
    !>
    !>          If UPLO = 'L':
    !>               If IPIV(k) > 0, then rows and columns k and IPIV(k)
    !>               were interchanged and D(k,k) is a 1-by-1 diagonal block.
    !>               (If IPIV( k ) = k, no interchange was done).
    !>
    !>               If IPIV(k) = IPIV(k+1) < 0, then rows and
    !>               columns k+1 and -IPIV(k) were interchanged,
    !>               D(k:k+1,k:k+1) is a 2-by-2 diagonal block.
    !>

    B

    !>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
    !>          On entry, B contains NRHS vectors of length N.
    !>          On exit, B is overwritten with the product A * B.
    !>

    LDB

    !>          LDB is INTEGER
    !>          The leading dimension of the array B.  LDB >= max(1,N).
    !>

    INFO

    !>          INFO is INTEGER
    !>          = 0: successful exit
    !>          < 0: if INFO = -k, the k-th argument had an illegal value
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 153 of file dlavsy.f.

Author

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