Function

# vDSP_polarD

Converts double-precision rectangular coordinates to polar coordinates, using the specified stride.

## Parameters

`__A`

Double-precision real input vector.

`__IA`

Stride for `A`, must be even.

`__C`

Double-precision output vector.

`__IC`

Stride for `C`, must be even.

`__N`

Number of ordered pairs processed.

## Discussion

This performs the following operation:

Converts rectangular coordinates to polar coordinates. Vector `A` defines Cartesian (x, y) pairs. The function writes polar (rho, theta) pairs, where rho is the radius and theta is the angle in the range `[-pi, pi]` to vector `C`. `N` specifies the number of coordinate pairs in `A` and `C`.

Coordinate pairs are adjacent elements in the array, regardless of stride; stride is the distance from one coordinate pair to the next.

The following code shows how to convert a single pair of rectangular coordinates to their polar equivalent.

On return, `radius` is `7.07`, and `angle` is `45`.

This function performs the inverse operation of `vDSP_rect`, which converts polar to rectangular coordinates.

### Single-Vector Polar-Rectangular Conversion

`vDSP_polar`

Converts single-precision rectangular coordinates to polar coordinates, using the specified stride.

`vDSP_rect`

Converts single-precision polar coordinates to rectangular coordinates, using the specified stride.

`vDSP_rectD`

Converts double-precision polar coordinates to rectangular coordinates, using the specified stride.