(S|D|C|Z)AXPY
==============
Single, double, single complex, and double complex AXPY.

Description
-----------
Scales the vector :math:`x` and adds to vector :math:`y`.

.. math::

  y \assign \alpha x + y

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

    void saxpy(const qml_long *N, const float *ALPHA, const float *X,
               const qml_long *INCX, float *Y, const qml_long *INCY);

    void daxpy(const qml_long *N, const double *ALPHA, const double *X,
               const qml_long *INCX, double *Y, const qml_long *INCY);

    void caxpy(const qml_long *N, const qml_single_complex *ALPHA,
               const qml_single_complex *X, const qml_long *INCX,
               qml_single_complex *Y, const qml_long *INCY);

    void zaxpy(const qml_long *N, const qml_double_complex *ALPHA,
               const qml_double_complex *X, const qml_long *INCX,
               qml_double_complex *Y, const qml_long *INCY);

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

    void cblas_saxpy(const qml_long N, const float ALPHA, const float *X,
                     const qml_long INCX, float *Y, const qml_long INCY);

    void cblas_daxpy(const qml_long N, const double ALPHA, const double *X,
                     const qml_long INCX, double *Y, const qml_long INCY);

    void cblas_caxpy(const qml_long N, const qml_single_complex *ALPHA,
                     const qml_single_complex *X, const qml_long INCX,
                     qml_single_complex *Y, const qml_long INCY);

    void cblas_zaxpy(const qml_long N, const qml_double_complex *ALPHA,
                     const qml_double_complex *X, const qml_long INCX,
                     qml_double_complex *Y, const qml_long INCY);

Arguments
-----------
=====   ================================================
N       Number of elements in X and Y
ALPHA   Scalar to scale vector X by
X       First input vector, must be at least: :math:`(\fvar{N}-1)\mult\abs{\fvar{INCX}} + 1`
INCX    Distance between individual elements in X
Y       Second input vector, must be at least: :math:`(\fvar{N}-1)\mult\abs{\fvar{INCY}} + 1`
INCY    Distance between individual elements in Y
=====   ================================================
