# Mathematica returns an empty plot for the real part of the eigenvalues [closed]

I have a 3*3 matrix. Using Mathematica I have found the eigenvalues in terms of "K". The problem arises when I'm plotting the real part of eigenvalues against "k" (k is a positive number ranging from 0.02 to 0.05). Can someone guide me, why I'm getting empty?

(*Here is my Matrix*)

J1 = {{-v^2 - w^2 - F - D1*k^2, -2*u*v, -2*u*w}, {v^2,
2*u*v - (F + k1) - D2*k^2, 0}, {w^2, 0,
2*u*w - (F + k2) - D3*k^2}};

(*I have defined the eigen values as the function of the following \
parameters*)
{λ4[F_, D1_, D2_, D3_, k1_, k2_, u_, v_,
w_], λ5[F_, D1_, D2_, D3_, k1_, k2_, u_, v_,
w_], λ6[F_, D1_, D2_, D3_, k1_, k2_, u_, v_, w_]} =
Eigenvalues[J1];

(*Here are the numerical values of the parameters*)
{λ4[0.025,
290, 61.443, 11, 0.0043, 0.046, 0.381, 0.0767, 0.186], λ5[
0.025, 290, 61.443, 11, 0.0043, 0.046, 0.381, 0.0767,
0.186], λ6[0.025, 290, 61.443, 11, 0.0043, 0.046, 0.381,
0.0767, 0.186]};

(*Plotting the real part of the eigen values against k*)
Plot[{Re[λ1], Re[λ2], Re[λ3]}, {k, 0.01, 0.05},
PlotStyle -> {{Thick, Red}, {Thick, Blue}}, Frame -> True,
FrameLabel -> {Style["k", 18], Style["Re(λ)", 18]}]

• You are plotting \[Lambda]1] , \[Lambda]2] and \[Lambda]3] but you did not define them. – Daniel Huber Apr 7 at 11:45

Is this what you want?

 {np1 = \[Lambda]4[0.025, 290, 61.443, 11, 0.0043, 0.046, 0.381,
0.0767, 0.186],
np2 = \[Lambda]5[0.025, 290, 61.443, 11, 0.0043, 0.046, 0.381,
0.0767, 0.186],
np3 = \[Lambda]6[0.025, 290, 61.443, 11, 0.0043, 0.046, 0.381,
0.0767, 0.186]}


and then

    Plot[{Re[np1], Re[np2], Re[np3]}, {k, 0.01, 0.05}, PlotStyle -> {{Thick, Red}, {Thick, Blue}}, Frame -> True, FrameLabel -> {Style["k", 18], Style["Re(\[Lambda])", 18]}]


• Thanks a lot, dear. Really appreciate it. Exactly that's what I wanted. – Albert Apr 7 at 17:26