(S|D)SBMV
=============
Single and double SBMV.

Description
-----------
Computes a symmetric banded matrix-vector product.

.. math::

    y \assign \alpha A * x + \beta y

BLAS Interface
--------------
.. code-block:: c

    void ssbmv(const char *UPLO, const qml_long *N, const qml_long *K,
               const float *ALPHA, const float *A, const qml_long *LDA,
               const float *X, const qml_long *INCX, const float *BETA,
               float *Y, const qml_long *INCY);

    void dsbmv(const char *UPLO, const qml_long *N, const qml_long *K,
               const double *ALPHA, const double *A, const qml_long *LDA,
               const double *X, const qml_long *INCX, const double *BETA,
               double *Y, const qml_long *INCY);


CBLAS Interface
---------------
.. code-block:: c

    void cblas_ssbmv(const CBLAS_ORDER ORDER, const CBLAS_UPLO UPLO, const qml_long N,
                     const qml_long K, const float ALPHA, const float *A,
                     const qml_long LDA, const float *X, const qml_long INCX,
                     const float BETA, float *Y, const qml_long INCY);

    void cblas_dsbmv(const CBLAS_ORDER ORDER, const CBLAS_UPLO UPLO, const qml_long N,
                     const qml_long K, const double ALPHA, const double *A,
                     const qml_long LDA, const double *X, const qml_long INCX,
                     const double BETA, double *Y, const qml_long INCY);


Arguments
---------
======   =====================================================================
UPLO     Specify whether the upper or lower triangle of matrix A will be used
N        Order of matrix A
K        Number of super-diagonals of A, with :math:`0 \le \fvar{K}`
ALPHA    Scalar multiplied with the matrix-vector product
A        Input matrix A
LDA      Leading dimension of matrix A, with :math:`\fvar{LDA} \ge \fvar{K}+1`
X        First input vector, must be at least: :math:`(\fvar{N}-1)\mult\abs{\fvar{INCX}} + 1`
INCX     Distance between individual elements in X
BETA     Scalar multiplied with vector Y
Y        Second vector, must be at least: :math:`(\fvar{N}-1)\mult\abs{\fvar{INCY}} + 1`
INCY     Distance between individual elements in Y
======   =====================================================================
