(i)), a cubic spline interpolant S(x) is defined as:</p>
<pre>
         S1(x)       x(1) &lt; x &lt; x(2)
 S(x) =   ...         
         Sn-1(x)   x(n-1) &lt; x &lt; x(n)
 </pre><p>where</p>
<pre> 
 Si(x) = a_i+b_i(x-xi)+c_i(x-xi)^2+d_i(x-xi)^3    i=1, ..., n-1
 </pre><dl class="section user"><dt>Algorithm</dt><dd></dd></dl>
<p>Having defined h(i) = x(i+1) - x(i)</p>
<pre>
 h(i-1)c(i-1)+2[h(i-1)+h(i)]c(i)+h(i)c(i+1) = 3/h(i)*[a(i+1)-a(i)]-3/h(i-1)*[a(i)-a(i-1)]    i=2, ..., n-1
 </pre><p>It is possible to 