orter of the two distances
between two sites and the common downstream junction, \(r1 = A / range\),
\(B\) be a matrix that contains the longer of the two distances between two sites and the
common downstream junction, \(r2 = B / range\),  and \(I\) be an identity matrix.
Then parametric forms for flow-unconnected elements of \(R(zd)\) are given below:</p><ul><li><p>linear: \((1 - r2) * (r2 &lt;= 1)\)</p></li>
<li><p>spherical: \((1 - 1.5r1 + 0.5r2) * (1 - r2)^2 * (r2 &lt;= 1)\)</p></li>
<li><p>exponential: