# Legacy Document

Important: The information in this document is obsolete and should not be used for new development.

Inside Macintosh: QuickDraw GX Environment and Utilities /
Chapter 8 - QuickDraw GX Mathematics / QuickDraw GX Mathematics Reference
Mathematical Functions / Cartesian and Polar Coordinate Point Conversions

### PointToPolar

The `PointToPolar` function converts a point in Cartesian coordinates to the identical point in polar coordinates.

```gxPolar *PointToPolar(const gxPoint *xy, gxPolar *ra);
```
`xy`
A pointer to the Cartesian coordinate.
`ra`
A pointer to the destination of the resulting polar coordinate.
function result
The pointer passed in `ra.`
##### DESCRIPTION
The `PointToPolar` function converts the Cartesian coordinate point (x, y) to the identical polar coordinate point (r, a). The parameters of the `PointToPolar` function are a `gxPoint` structure pointer `xy` and a `gxPolar` structure pointer `ra`.

If both pointers point to the same location, the source `gxPoint` structure will be converted to a `gxPolar` structure and will replace the `gxPoint` structure.

The `gxPolar` structure is described in the section "Constants and Data Types" beginning on page 8-35. The `PolarToPoint` function converts a point in polar coordinates to the identical point in Cartesian coordinates. The `PolarToPoint` function is described in the previous section.