### Coordinate Transforms

Is there something in sage that does the same thing that `CoordinateTransform`

and `TransformedField`

in Mathematica 9 ?

The idea is that `CoordinateTransform`

is given some coordinates, e.g. (r,th) and asked to transform them from "polar" to "cartesian", thus gives the expression of the cartesian coordinates in terms of the polar coordinates, e.g.

```
(x(r,th), y(r,th)) = (r*cos(th), r*sin(th))
```

Obvioulsly, it also works with other coordinates systems.

`TransformedField`

makes the transformation between a scalar, vector, or tensor field in, say, cartesian coordinates, to spherical coordinates.

These actions are not very complicated, nor difficult to implement when needed, but they are also very common.

Thanks.

references :

- http://reference.wolfram.com/mathematica/ref/CoordinateTransform.html
- http://reference.wolfram.com/mathematica/ref/TransformedField.html