zero, and
    \(A3\) can be zero or non-zero.
    Furthermore, we need to generate both \(x\) and \(y\) versions
    to provide the two components of the vector function \(C(t)\).
    Not all of those scenarios can actually occur, but because we
    are programmatically generating the equations, it is easier,
    and costs no more, to generate all 16 scenarios.
  </p>
    <p>
    The <code>xsplineFunGenerator</code> function was written to
    generate an expression for a specific scenario.  The following
 