Convert line spectral frequencies to prediction filter coefficients
a = lsf2poly(lsf)
a = lsf2poly(lsf) returns a vector, a, containing the prediction filter coefficients from the vector, lsf, of line spectral frequencies. If lsf is a matrix of size M × N with separate channels of line spectral frequencies in each column, the returned a matrix has the resulting prediction filter coefficients as its rows and is of size N × (M + 1).
Given a vector, lsf, of line spectral frequencies, determine the equivalent prediction filter coefficients.
lsf = [0.7842 1.5605 1.8776 1.8984 2.3593]; a = lsf2poly(lsf)
a = 1.0000 0.6148 0.9899 0.0001 0.0031 -0.0081
 Deller, John R., John G. Proakis, and John H. L. Hansen. Discrete-Time Processing of Speech Signals. New York: Macmillan, 1993.
 Rabiner, Lawrence R., and Ronald W. Schafer. Digital Processing of Speech Signals. Englewood Cliffs, NJ: Prentice-Hall, 1978.