order-decreasing backward layer recursion
[r,A,B] = bkwrec(a,b)
order-M reflection polynomials
number of layers
reflection coefficients = [r(1),...,r(M+1)]
(M+1)x(M+1) matrices whose columns are the reflection polynomials
bkwrec(a,b) performs order-decreasing backward layer recursion - from a,b to r
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