Function

# vDSP_rectD

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

## Parameters

`__A`

Double-precision real input vector.

`__IA`

Stride for `A`, must be even.

`__C`

Double-precision real output vector.

`__IC`

Stride for `C`, must be even.

`__N`

Number of ordered pairs processed.

## Discussion

This performs the following operation:

Converts polar coordinates to rectangular coordinates. Vector `A` defines polar (rho, theta) pairs, where rho is the radius and theta is the angle in the range `[-pi, pi]`. The function writes Cartesian (x, y) pairs 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 an angle-radius pair (with the angle specified in degress) to its rectangular equivalent.

On return, `rectangularCoordinates` contains `[5, 5]`.

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

### Single-Vector Polar-Rectangular Conversion

`vDSP_polar`

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

`vDSP_polarD`

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

`vDSP_rect`

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