Notes for AXPY

1. Performs $y \leftarrow \alpha x + y$
2. An index file input line looks like:

   <ID> <alpha> <incX> <incY> <source file> <author name>
   

3. The kernel will never be called with alpha == 0.0.
4. For complex, if both vector strides are 1, and the imaginary component of alpha is zero, the real kernel is called with 2*N.