Signal Processing Toolbox

poly2ac

Convert a prediction filter polynomial to an 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	Convert an autocorrelation sequence to a prediction filter polynomial.
poly2rc	Convert a prediction filter polynomial to reflection coefficients.
rc2ac	Convert reflection coefficients to an autocorrelation sequence.

References

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

pmusic

poly2lsf