1) z=a is called a pole of f(z) if |f(z)| approaches infinity as z approaches a.
2) z = a is called a zero of f(z) if f(a) = 0.
3) X is a vector space over a field F, if
(i) there is a binary operation + defined on X
such that (X, +) is a commutative group, and
(ii) there is a scalar multiplication operation .
which is defined for each element a of F and
x of X such that ax is in X, and satisfying
the distributive laws a(x + y) = ax + ay,
a(bx) = (ab)x.