I tried this example from the site:

https://cadabra.science/manual/PartialDerivative.html

```
\tau::Coordinate;
\partial{#}::Derivative(\tau);
f::Depends(\tau);
ex:= \partial{f g};
unwrap(ex);
```

It returns 0 instead of g∂f

0 votes

I tried this example from the site:

https://cadabra.science/manual/PartialDerivative.html

```
\tau::Coordinate;
\partial{#}::Derivative(\tau);
f::Depends(\tau);
ex:= \partial{f g};
unwrap(ex);
```

It returns 0 instead of g∂f

+1 vote

The above works fine with the current version on github. If it does not for you,

either upgrade, or say explicitly that the derivative is with respect to $\tau$,

```
ex:= \partial_{\tau}{ f g};
```

or make $f$ depend on `\partial`

:

```
f::Depends(\partial{#}).
```

Otherwise the 'old' version of Cadabra which you use does not know how to figure out that `\partial`

is a $\tau$-derivative.

...