Signal Processing Toolbox

ac2poly

Convert an autocorrelation sequence to a prediction filter polynomial.

Syntax

a = ac2poly(r)
[a,efinal] = ac2poly(r)

Description

a = ac2poly(r) finds the prediction filter polynomial a corresponding to the autocorrelation sequence r. a is the same length as r, and a(1) = 1. The prediction filter polynomial represents the coefficients of the prediction filter whose output produces a signal whose autocorrelation sequence is approximately the same as the given autocorrelation sequence r.

[a,efinal] = ac2poly(r) returns the final prediction error efinal, determined by running the filter for length(r) steps.

Remarks

You can apply this function to real or complex data.

Example

Consider the autocorrelation sequence

r = [5.0000 -1.5450 -3.9547 3.9331 1.4681 -4.7500];

The equivalent prediction filter polynomial is

[a,efinal] = ac2poly(r)
a =
    1.0000    0.6147    0.9898    0.0004    0.0034   -0.0077
efinal =
    0.1791

See Also

ac2rc	Convert an autocorrelation sequence to reflection coefficients.
poly2ac	Convert a prediction filter polynomial to an autocorrelation sequence.
rc2poly	Convert reflection coefficients to a prediction filter polynomial.

References

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

abs

ac2rc