function [a1,b1,e,V1,st]=gstep(x,a,b,g,V,p,q)
% Searches for lower values of V in the direction of g
%
% Programmed by: Dimitris Manolakis, 9/29/93
% Revised: 1/7/94
%
%-----------------------------------------------------------
% Copyright 2000, by Dimitris G. Manolakis, Vinay K. Ingle,
% and Stephen M. Kogon.  For use with the book
% "Statistical and Adaptive Signal Processing"
% McGraw-Hill Higher Education.
%-----------------------------------------------------------



it=0; k=1; pq=p+q; st=0; V1=V+1;
pqmax=max([p q]);
Lx=length(x);

while [V1>V it<10]
  a1=a+k*[0 g(1:p)']';
  b1=b+k*[0 g(p+1:p+q)']';
  if it==9, a1=a;, b1=b; end
  b1=miphapol(b1);b1=b1(:);
  e=pefilter(a1,b1,x);
  V1=e'*e/(length(e)-pqmax);
k=k/2;
it=it+1;
if it==10, st=1; end
end