`On each subinterval we have a cubic polynomial .
To obtain a very smooth, good-looking curve with
minimal unwanted oscillations
we impose that the function is twice continuously differentiable.
This means that we impose the continuity, countinuous first derivative and
continuous second derivative conditions at all intermediate points:
`

`The length of the interval is
`

`The piecewise cubic polynomials have the form:
`

Adrian Sandu 2001-08-26