poly2ac

Convert prediction filter polynomial to autocorrelation sequence

Syntax

r = poly2ac(a,efinal)

Description

r = poly2ac(a,efinal) returns the autocorrelation vector, r, corresponding to the autoregressive prediction filter polynomial, a, and the final prediction error, efinal. r is approximately equal to the autocorrelation of the output of a prediction filter with coefficients a. If a(1) is not equal to 1, poly2ac normalizes the prediction filter polynomial by a(1). a(1) cannot be 0.

Examples

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Autocorrelation Sequence from Prediction Filter

Given a prediction filter polynomial, a, and a final prediction error, efinal, find the autocorrelation sequence.

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

More About

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Tips

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

References

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

See Also

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