function b = numf(h,a,nb)
%NUMF	Find numerator B given impulse-response h of B/A and denominator A
%	NB is the numerator order.  This function is used by YULEWALK.
  
nh = max(size(h)); 
impr = filter(1,a,[1 zeros(1,nh-1)]);
b = h/toeplitz(impr,[1 zeros(1,nb)])';

