Dear Kasper, thank you for the answer. Actually, as you pointed, the equal sign assigns the value to `A00`

. However, it seems that I cannot use the value for further manipulations.

I'm trying to write a demo notebook for students, and it occurs to me that it might be possible to solve the Schwarzschild spacetime. I got inspired by your notebook, but used

```
ss:= { g_{t t} = - \exp(A),
g_{r r} = \exp(B),
g_{\theta\theta} = r**2,
g_{\phi\phi}=r**2 \sin(\theta)**2 }.
```

for the metric.

After calculating the Ricci tensor `rc`

, I call the components,

```
from cdb.core.component import *
r00=get_component(rc, $t,t$)[1];
r11=get_component(rc, $r,r$)[1];
```

but then I cannot use those expressions (it seems)

See image