poly2ac (Signal Processing Toolbox)

Convert prediction filter polynomial to autocorrelation sequence

Syntax

```
r = poly2ac(a,efinal)
```

Description

r = poly2ac(a,efinal) finds the autocorrelation vector r corresponding to the prediction filter polynomial a. The autocorrelation sequence produced is approximately the same as that of the output of the autoregressive prediction filter whose coefficients are determined by a. poly2ac also produces the final length(r) step prediction error efinal. If a(1) is not equal to 1, poly2ac normalizes the prediction filter polynomial by a(1). a(1) cannot be 0.

Remarks

You can apply this function to both real and complex polynomials.

Examples

a = [1.0000    0.6147    0.9898    0.0004    0.0034   -0.0077];
efinal = 0.2;
r = poly2ac(a,efinal)
r =
    5.5917
   -1.7277
   -4.4231
    4.3985
    1.6426
   -5.3126

See Also

ac2poly, poly2rc, rc2ac

References

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

pmusic poly2lsf