TESTING/LIN/slavsy.f(3)

NAME
TESTING/LIN/slavsy.f

SYNOPSIS

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

Function/Subroutine Documentation

  subroutine slavsy (character uplo, character trans, character diag, integer n, integer nrhs, real, dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, real, dimension( ldb, * ) b, integer ldb, integer info)

SLAVSY

Purpose:

     SLAVSY  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 SSYTRF.
     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 REAL array, dimension (LDA,N)
              The block diagonal matrix D and the multipliers used to
              obtain the factor U or L as computed by SSYTRF.
              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 SSYTRF.
              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 REAL 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 slavsy.f.

Author

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