Figure 6From: Numerical scheme and dynamic analysis for variable-order fractional van der Pol model of nonlinear economic cycle Phase plot for the VOFVDPM with different periodical functions, \(\pmb{a=0}\) , \(\pmb{\mu=2.5}\) , and \(\pmb{(x(0),y(0))=(1.3,1.2)}\) . Back to article page