### Plotting eigenvalues as a function of a variable

I am attempting to plot the the eigenvalues for the matrix:

```
H=matrix([[1+x, 0, x],[0, 2, 2*x],[x, 2*x, 1+x]])
```

which were calculated using the following method:

```
a=H.eigenvalues()
```

in the following way:

```
h=fast_callable(real_part(a[2]),vars=[x],domain=CC)
plot(h,(0,0.5))
```

but unfortunately this does not work for the a[0] and ~~a[1]. ~~a[1],

```
f=fast_callable(real_part(a[0]),vars=[x],domain=CC)
g=fast_callable(real_part(a[1]),vars=[x],domain=CC)
plot(f,(0,0.5))+plot(g,(0,0.5))
```

Any suggestions would be greatly appreciated.