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# vDSP_zcspec

Computes the cross-spectrum of two complex single-precision vectors.

```
extern void vDSP_zcspec(const DSPSplitComplex *__A, const DSPSplitComplex *__B, const DSPSplitComplex *__C, vDSP_Length __N);
```

## Parameters

`__A`

Single-precision complex input vector with a stride of 1.

`__B`

Single-precision complex input vector with a stride of 1.

`__C`

Single-precision complex input-output vector, with a stride of 1.

`__N`

The number of elements to process.

## Discussion

This function computes the cross-spectrum of complex input vectors `A` and `B`: it multiplies elements of `B` by the complex conjugates of elements of `A`. The results are added to complex input-output vector `C`. `C` should contain valid  data from previous processing or should be initialized according to your needs before calling this function.

![mathematical formula](images/com.apple.accelerate/media-2557786@2x.png)

---

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