Fig. 11

Behaviour of Eq.(7.2) with the parameters \(\sigma = 1, \; \gamma = 1, \; \tau =4, \; \theta = -1, \; \alpha = -2, \; d = 8 \;\) and \(\;k = -1.2\) , with initial values (0.7, 0.2) in red and (0.7, 1.5) in green.

Behaviour of Eq.(7.2) with the parameters \(\sigma = 1, \; \gamma = 1, \; \tau =4, \; \theta = -1, \; \alpha = -2, \; d = 8 \;\) and \(\;k = -1.2\) , with initial values (0.7, 0.2) in red and (0.7, 1.5) in green.