# Plot a quartic expression with two variables?

Posted 2 years ago
2085 Views
|
4 Replies
|
2 Total Likes
|
 Hi guys, new user here...trying to figure out what I'm missing hereThe idea is to get a graph similar to this one m = 10; Jp = 2; Jt = 1.2; l = 0.2; k12 = 0; ka = 2.5*(10^6); k11 = 2*ka; k22 = (0.5^2 + 0.5^2)*ka; Eqt = \[Omega]^4 - \[Omega]^3*\[CapitalOmega]*(Jp/ Jt) - \[Omega]^2 ((k11/m) + (k22/ Jt)) + \[Omega]*\[CapitalOmega]*((k11*Jp)/(m*Jt)) + ((k11* k22 - k12^2)/(m*Jt)) == 0 Plot[Eqt, {\[Omega], -1000, 1500}, {\[CapitalOmega], 0, 1500}] The Eqt term is the quartic equation and there is two variables ? and ? (abscissae). I could only plot3d it... any suggestions to plot like the graph above.cheers, Answer
4 Replies
Sort By:
Posted 2 years ago
 I think you need to solve Eqt Answer
Posted 2 years ago
 You can use ContourPlot: ContourPlot[Evaluate[Eqt], {\[Omega], -1000, 1500}, {\[CapitalOmega], -4000, 4000}] Answer
Posted 2 years ago
 In:= Solve[Eqt, \[Omega]] During evaluation of In:= Solve::ratnz: Solve was unable to solve the system with inexact coefficients. The answer was obtained by solving a corresponding exact system and numericizing the result. Out= {{\[Omega] -> -707.107}, {\[Omega] -> 707.107}, {\[Omega] -> 0.833333 (\[CapitalOmega] - 1. Sqrt[1.5*10^6 + \[CapitalOmega]^2])}, {\[Omega] -> 0.833333 (\[CapitalOmega] + Sqrt[1.5*10^6 + \[CapitalOmega]^2])}} In:= Plot[ 0.8333333333333334 (\[CapitalOmega] + Sqrt[ 1.5*^6 + \[CapitalOmega]^2]), {\[CapitalOmega], 0, 1000}] Answer
Posted 2 years ago
 Hi guys, I appreciate the feedback. I could figure it out by solving the equation... Eqt = \[Omega]^4 - \[Omega]^3*\[CapitalOmega]*(Jp/ Jt) - \[Omega]^2 ((k11/m) + (k22/ Jt)) + \[Omega]*\[CapitalOmega]*((k11*Jp)/(m*Jt)) + ((k11* k22 - k12^2)/(m*Jt)) == 0; Es = \[Omega] /. Solve[Eqt, \[Omega]] Plot[Es, {\[CapitalOmega], 0, 1500}] Thanks, again Answer