# ac2rc

Convert autocorrelation sequence to reflection coefficients

## Syntax

``[k,r0] = ac2rc(r)``

## Description

````[k,r0] = ac2rc(r)` returns the reflection coefficients, `k`, from the autocorrelation sequence `r`. The `ac2rc` function also returns the zero-lag autocorrelation `r0`. ```

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## Examples

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Given an autocorrelation sequence, `r`, determine the reflection coefficients of the corresponding lattice structure and the zero-lag autocorrelation.

```r = [5.0000 -1.5450 -3.9547 3.9331 1.4681 -4.7500]'; [k,r0] = ac2rc(r)```
```k = 5×1 0.3090 0.9800 0.0030 0.0082 -0.0077 ```
```r0 = 5 ```

## Input Arguments

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Autocorrelation sequence, specified as a vector or as a matrix. The `ac2rc` function treats each column of `r` as a separate channel.

Data Types: `double`
Complex Number Support: Yes

## Output Arguments

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List of reflection coefficients, returned as a column vector or as a matrix. This list has as many columns (channels) as `r`, and p rows, where p+1 is the number of rows in `r`.

Zero-lag autocorrelation, returned as a scalar or as a column vector with as many rows as channels (columns) in `r`.

## Tips

You can use the reflection coefficients `k` to find the lattice prediction filter that produces a sequence with approximately the same autocorrelation sequence as the given sequence `r`. See `rc2poly` for more information

## References

[1] Kay, Steven M. Modern Spectral Estimation. Englewood Cliffs, NJ: Prentice-Hall, 1988.

## Version History

Introduced before R2006a

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