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# vDSP_venvlp

Calculates whether each element in a single-precision vector falls within a specified range.

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

## Parameters

`__A`

Single-precision real input vector: high envelope.

`__IA`

Stride for `A`.

`__B`

Single-precision real input vector: low envelope.

`__IB`

Stride for `B`.

`__C`

Single-precision real input vector.

`__IC`

Stride for `C`.

`__D`

Single-precision real output vector.

`__ID`

Stride for `D`.

`__N`

The number of elements to process.

## Discussion

Finds the extrema of `C`. For the first `N` elements of `C`, the corresponding element of `A` provides an upper-threshold value, and the corresponding element of `B` provides a  lower-threshold value. If the value of an element of `C` falls outside the range defined by these thresholds, it is copied to the corresponding element of `D`. If its value is within the range, the corresponding element of `D` is set to zero:

![mathematical formula](images/com.apple.accelerate/media-2557782@2x.png)

---

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