Reading Assignment:
  Today (Friday) we finished Section 6.2.  On Monday we 
     will proceed to Section 6.3 & 6.5.  Read Section 6.3 & 
     Section 6.5 up to but not including Example 1.
  
When reading:
  The primary focus of these sections is to add to our list
     of properties of the Laplace transform begun a few days 
     ago; and to compute the Laplace transform of some basic
     discontinuous functions.
  Section 6.3:
     1) What is the Heaviside function? 
     2) Laplace transform of a step function.
     3) Add to property list; behavior of the Laplace
            transform under translations and multiplication
            by exponentials.
  Section 6.5:
     What is an impulse function, and its Laplace transform?

Problems (due Wednesday 2/25):
  Section 6.2 : 1,2,4,7,12,13,18,21