` bifurcation[dmin_, dmax_, nd_, gamma_, A_, ndrop_, nplot_, psize_] := (T = 2*Pi/omega; g[{xold_, vold_}] := {x[T], v[T]} /. NDSolve[{v'[t] == 0.847 x[t] - 0.0721 x[t]^3 - gamma*v[t] + A*Cos[omega*t], x'[t] == v[t], x[0] == xold, v[0] == vold}, {x, v}, {t, 0, T}][[1]]; f[{x_, y_}] := {omega, x}; ListPlot[ Flatten[Table[ f /@ Drop[NestList[g, {1, 0}, nplot + ndrop], ndrop], {omega, dmin, dmax, (dmax - dmin)/nd}], 1], PlotStyle -> {PointSize[psize], Hue[0]}, AxesLabel -> {"\[Omega]", "x"}, AxesOrigin -> {dmin, -0.3}]) bifurcation[0.1, 0.8, 200, 0.01, 0.00172, 1200, 500, 0.006] `

I am expecting chaos around somewhere near omega=0.45 but instead I am getting just straight line.