We now formally give the following definition
Definition 4 Let  f  be a real valued function and let c be an interior point in the domain
of f Then
(a)
c is called a point of local maxima if there is an h > 0 such that
f (c) ≥ f (x), for all x in (c – h, c + h), x ≠ c
The value f (c) is called the local maximum value of f (b)
c is called a point of local minima if there is an h > 0 such that
f (c) ≤ f (x), for all  x in (c – h, c + h)
The value f (c) is called the local minimum value of f Geometrically, the above definition states that if  x = c is a point of local maxima of  f,
then the graph of f around c will be as shown in Fig 6