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# vDSP_f3x3

Filters a single-precision image by performing a 2D convolution with a 3 x 3 kernel.

```
extern void vDSP_f3x3(const float *__A, vDSP_Length __NR, vDSP_Length __NC, const float *__F, float *__C);
```

## Parameters

`__A`

Single-precision real input matrix.

`__NR`

The number of rows in `A`. The value of `NR` must be greater than or equal to 3.

`__NC`

The number of columns in `A`. The value of `NC` must be even and greater than or equal to 4.

`__F`

Single-precision real 3x3 kernel.

`__C`

Single-precision real result matrix.

## Discussion

This function filters an image by performing a two-dimensional convolution with a 3x3 kernel (`F`) on the input matrix `A` and storing the resulting image in the output matrix `C`.

This function zero-pads the perimeter of the output image with a border of width 1:

![mathematical formula](images/com.apple.accelerate/media-2557830@2x.png)

---

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