mment">% Compressibility coefficients</span>
            ccc =  phi * dSldpc;
            ccg = 0.0;
            cgc = -phi * dSldpc * (rhog / rhol);
            cgg =  phi * (1.0 - Sl) * drhogdpg / rhol;
        <span class="keyword">end</span>
        <span class="comment">%------------------------------------------------------------------</span>
        <span class="comment">% Compute the derivative of the gas density wrt to the gas pressure</span>
        <span class="keyword">function</span> drhogdpg =