The in- and out-degree distributions of a network generated by the CC model.

<p>The functions of the CC model are set as follows: <i>N</i>(<i>t</i>) = [e^0.1<i>t</i>], </p><p></p><p><mo stretchy="false">∣</mo></p><p><mi>D</mi><mi>i</mi></p><mo stretchy="false">∣</mo><mo>=</mo><p></p><p><mn>0</mn><mo>.</mo><mn>15</mn><mi>β</mi><mo stretchy="false">(</mo></p><p><mi>θ</mi><mi>i</mi></p><mo stretchy="false">)</mo><p></p><p><mo stretchy="false">[</mo></p><p>e</p><p><mn>0</mn><mo>.</mo><mn>1</mn></p><p><mi>t</mi><mi>i</mi></p><p></p><p></p><mo stretchy="false">]</mo><p></p><p></p><p></p><p></p>, and <i>β</i>(⋅) is given by <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0120687#pone.0120687.e005" target="_blank">Equation (2)</a>. The fitting functions in Panel (a) are the Poisson distribution <p></p><p><mi>f</mi><mo stretchy="false">(</mo><mi>k</mi><mo stretchy="false">)</mo><mo>=</mo></p><p><mi>a</mi><mi>k</mi></p><p></p><p>e</p><p><mo>−</mo><mi>a</mi></p><p></p><p><mi>k</mi><mo>!</mo></p><p></p><p></p><p></p> and the mixture Poisson distribution given by <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0120687#pone.0120687.e031" target="_blank">Equation (13)</a>. The fitting functions in Panel (b) are the power-law functions <i>f</i>(<i>k</i>) = <i>ak</i>⁻² and <p></p><p><mi>f</mi><mo stretchy="false">(</mo><mi>k</mi><mo stretchy="false">)</mo><mo>=</mo></p><p></p><p></p><p><mi>k</mi></p><p><mo>−</mo><mi>γ</mi></p><p></p><p></p><p></p><p></p><p><mo>∑</mo></p><p><mi>n</mi><mo>=</mo><mn>0</mn></p><mi>∞</mi><p></p><p></p><p></p><p><mo stretchy="false">(</mo><mi>n</mi><mo>+</mo></p><p><mi>x</mi></p><p><mi>min</mi></p><p></p><mo stretchy="false">)</mo><p></p><p><mo>−</mo><mi>γ</mi></p><p></p><p></p><p></p><p></p><p></p><p></p><p></p>.<p>