Dear friends, Over the past week, I tried to plot implicit function by mathematica but failed. I am very disappointed. Hopefully someone help me at this time. My equation is given by (see below figure): Where z0 := 6 d := 12 k := 11800 w0 := 0.025 w[z_] := sqrt[w0^2*(1 + (z/z0)^2)] deltaphi0[z_] := 0.6/(1 + (z^2/z0^2)) R[z_] := z*(1 + (z0/z)^2) wm0[z_] := sqrt[w^2/(2*m + 1)] dm[z_] := (k/2)*((wm0)^2) g[z_] := 1 + (d/R) wm[z_] := wm0*sqrt[[g^2 + (d)^2/dm^2]] Rm[z_] := d*(1 - g/(g^2 + (d/dm)^2))^(-1) thetam[z_] := ArcTan[d/(dm*g)] I want to plot a graph to represent the dependence of r (z). I have tried the following code-mathematica file But mathamatica plot 2 coordinate axes without data (no points). Please help me! This is the mathematica file https://docs.google.com/a/hcmus.edu.vn/file/d/0B6ue0CPI1AOFcWpjd19zMEU0a2s/edit and my function https://docs.google.com/a/hcmus.edu.vn/file/d/0B6ue0CPI1AOFTXMxRFZDaXd6NjQ/edit Thanks very much.