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# vDSP_biquadmD

Applies a double-precision multichannel biquadratic IIR filter.

```
extern void vDSP_biquadmD(vDSP_biquadm_SetupD __Setup, const double **__X, vDSP_Stride __IX, double **__Y, vDSP_Stride __IY, vDSP_Length __N);
```

## Parameters

`__Setup`

The biquadratic filter setup object that defines the filter the function applies.

`__X`

An array of pointers, each of which specifies an array of input data for a single channel.

`__IX`

The stride for the input.

`__Y`

On output, an array of pointers, each of which contains the output data for a single channel.

`__IY`

The stride for the output.

`__N`

The number of elements to filter.

## Discussion

For each channel, this function applies a cascaded biquad filter to the input values specified by the channel’s pointer in `X`, and places the results in the array specified by the corresponding pointer in `Y`.

This function supports interleaved channel data. In this case, define the stride as the number of channels, and the pointers to consecutive channels as consecutive locations in memory.

> Performance and Energy Efficiency:
> This function achieves the best performance and energy efficiency with non-interleaved data and a stride of 1, or interleaved data and a stride equal to the number of channels.

---

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