---
title: vDSP_biquadm_CreateSetupD
framework: Kernel
role: symbol
role_heading: Function
platforms: [macOS 10.10+]
path: kernel/1579944-vdsp_biquadm_createsetupd
---

# vDSP_biquadm_CreateSetupD

Builds a data structure that contains precalculated data for use by a double-precision, multichannel cascaded biquadratic filter function.

## Declaration

```occ
vDSP_biquadm_SetupD vDSP_biquadm_CreateSetupD(const double *__coeffs, vDSP_Length __M, vDSP_Length __N);
```

## Parameters

- `__Coefficients`: The input array that contains the double-precision filter coefficients. The number of elements in the coefficients array must be five times the number of sections in the biquad filter.
- `__M`: The number of sections in the biquad filter.
- `__N  `: The number of input-output channels.

## Return Value

Return Value A pointer to an allocated and initialized biquadratic filter object.

## Discussion

Discussion This function constructs and returns a biquadratic filter object from the coefficients that you specify. This function initializes the internal state of the setup object with all delay elements set to zero. You define the __Coefficients array as a series of sections with each containing a set of five coefficients. Specify the order of the coefficients as three feedforward coefficients followed by two feedback coefficients. The following code shows an example of creating a biquad setup object that contains two sections: let section0 = (b0: 0.984764420,                 b1: -1.969528840,                 b2: 0.984764420,                 a1: -1.969331359,                 a2: 0.969726321)

let section1 = (b0: 0.984764420,                 b1: -1.969528840,                 b2: 0.984764420,                 a1: -1.955243388,                 a2: 0.969726321)

let sectionCount = vDSP_Length(2) let channelCount = vDSP_Length(1)

let setup = vDSP_biquadm_CreateSetupD([     section0.b0, section0.b1, section0.b2, section0.a1, section0.a2,     section1.b0, section1.b1, section1.b2, section1.a1, section1.a2 ],                                       sectionCount,                                       channelCount) This function allocates memory for its own use. You must call the vDSP_biquadm_DestroySetupD function to free the allocated memory.