We must now investigate the integral
To evaluate the integral we use a common trick in physics and insert
a slight convergence factor 
which we later
``turn off" by taking the limit 
at the end of the day.
We
then have,
So,
which appears like a very tall narrow spike of height 
and width 
as in Figure 3.4.1.
The height grows and width shrinks so that the area is always constant,
The 
-function has two basic properties from which others may be
derived:
