---
title: vDSP_vmmsb
framework: Accelerate
role: symbol
role_heading: Function
platforms: [iOS 4.0+, iPadOS 4.0+, Mac Catalyst 13.1+, macOS 10.4+, visionOS 1.0+, watchOS 2.0+]
path: accelerate/vdsp_vmmsb
---

# vDSP_vmmsb

Calculates the single-precision element-wise difference of the products of two pairs of vectors, using the specified stride.

## Declaration

```occ
extern void vDSP_vmmsb(const float *__A, vDSP_Stride __IA, const float *__B, vDSP_Stride __IB, const float *__C, vDSP_Stride __IC, const float *__D, vDSP_Stride __ID, float *__E, vDSP_Stride __IE, vDSP_Length __N);
```

## Parameters

- `__A`: The input vector A in E = (A * B) - (C * D).
- `__IA`: The distance between the elements in the input vector A.
- `__B`: The input vector B in E = (A * B) - (C * D).
- `__IB`: The distance between the elements in the input vector B.
- `__C`: The input vector C in E = (A * B) - (C * D).
- `__IC`: The distance between the elements in the input vector C.
- `__D`: The input vector D in E = (A * B) - (C * D).
- `__ID`: The distance between the elements in the input vector D.
- `__E`: The output vector E in E = (A * B) - (C * D).
- `__IE`: The distance between the elements in the output vector E.
- `__N`: The number of elements that the function processes.

## Mentioned in

Using vDSP for vector-based arithmetic

## Discussion

Discussion This function calculates the differences of the first N elements of the product of vectors A and B and the product of vectors C and D, as follows:  for (n = 0; n < N; ++n)     E[n] = A[n]*B[n] - C[n]*D[n];

The following code shows an example of using this function:

## See Also

### Quaternary multiply-multiply-subtract operations

- [vDSP_vmmsbD](accelerate/vdsp_vmmsbd.md)