Hello,

This looks like a bug. Please do submit a PR.

Thanks
Faisal Riyaz

On Thu, Aug 27, 2020 at 4:10 AM Alexander Lindsay <[email protected]>
wrote:

> This patch fixes the bad behavior:
>
> diff --git a/sympy/vector/operators.py b/sympy/vector/operators.py
> index 2f303ee690..994894f379 100644
> --- a/sympy/vector/operators.py
> +++ b/sympy/vector/operators.py
> @@ -362,6 +362,4 @@ def _diff_conditional(expr, base_scalar, coeff_1,
> coeff_2):
>      """
>      from sympy.vector.functions import express
>      new_expr = express(expr, base_scalar.system, variables=True)
> -    if base_scalar in new_expr.atoms(BaseScalar):
> -        return Derivative(coeff_1 * coeff_2 * new_expr, base_scalar)
> -    return S.Zero
> +    return Derivative(coeff_1 * coeff_2 * new_expr, base_scalar)
>
> Should I submit a PR?
>
> On Wed, Aug 26, 2020 at 3:30 PM Alexander Lindsay <
> [email protected]> wrote:
>
>> Execution of the below code:
>>
>> From sympy.vector import divergence, gradient, Vector, CoordSys3D
>> R = CoordSys3D('R', transformation='cylindrical')
>> divergence(R.i)
>>
>> generates a zero result. I believe the result should be 1/r, right?
>>
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