- #1

Saladsamurai

- 3,019

- 6

**Mathematica: Div in Cylindrical and "Shadowing"**

I have a vector given in cylindrical coordinates. I know that the divergence of the vector should be zero. However, I am not sure why Mathematica is not returning zero. Also, the Div operator is showing up red (Div) and it is saying something about Shadowing. I have no idea what this means and the help is a little cryptic about it. I tried using Remove[Div] but it is protected. I am not sure what to do about that. This is the code i am using:

Code:

```
Clear["Global`*"]
Needs["VectorAnalysis`"]
Vr = (A/r^2 - B) Cos[theta];
Vtheta = (A/r^2 + B) Sin[theta];
Div[{Vr, Vtheta, 0}, Cylindrical[r, theta, z]]
```

which should give zero, but instead it gives me an algebraic expression.