conditional execution of the Multiply-and-Accumulate.
Horizontal-First Mode is the standard Cray-Style Vectorisation:
loop on all *elements* with the same instruction before moving
-on to the next instruction. Predication needs to be pre-calculated
+on to the next instruction. Horizontal-First
+Predication needs to be pre-calculated
for the entire Vector in order to exclude certain elements from
the computation. In this case, that's an expensive inconvenience
-(similar to the problems associated with Memory-to-Memory
+(remarkably similar to the problems associated with Memory-to-Memory
Vector Machines such as the CDC Star-100).
Vertical-First allows *scalar* instructions and