We start our journey with the curve C parameterized by
 
 
with the parameter t ranging in value from a to b (ie.  
 .)
The curve is now said to be oriented since we have a definite direction of 
travel along C.
Next, for those destructive gremlins out there, break the curve up into N
segements.  The image below shows the curve broken into N = 5 pieces.

At each of the N + 1 points we need to compute two things:  the tangent
vector  
  and the vector field,  
 .