1. <mathematics> A single number, as opposed to a vector or
matrix of numbers. Thus, for example, "scalar
multiplication" refers to the operation of multiplying one
number (one scalar) by another and is used to contrast this
with "matrix multiplication" etc.
2. <architecture> In a parallel processor or vector
processor, the "scalar processor" handles all the sequential
operations - those which cannot be parallelised or vectorised.
See also superscalar.
3. <programming> Any data type that stores a single value
(e.g. a number or Boolean), as opposed to an aggregate
data type that has many elements. A string is regarded as a
scalar in some languages (e.g. Perl) and a vector of
characters in others (e.g. C).
