Figure 4
Phase portrait analysis of the dynamical system (17) at critical points. (a) Effect of \(\sigma _1 S\) on the planar system (17), assuming \(\sigma _1=1\), \(\sigma _2>0\) and \(\sigma _3>0\). (b) Effect of \(\sigma _1 S\) on the planar system (17), assuming \(\sigma _1=0.7\), \(\sigma _2>0\) and \(\sigma _3>0\). (c) Effect of \(\sigma _1 S\) on the planar system (17), assuming \(\sigma _1=0.3\), \(\sigma _2>0\) and \(\sigma _3>0\). (d) Effect of \(\sigma _1 S\) on the planar system (17), assuming \(\sigma _1=0\), \(\sigma _2>0\) and \(\sigma _3>0\).
