global Pkmi_array
m=(length(data_frame)-1)/2;
N=length(data_frame);
x=-m:m;
y=data_frame;
x=x(:);
y=y(:);
k_start=2;
k_end=N-1-2;
alpha=0.01;
if k_end<=k_start
polynomial_degree=k_start;
return;
else
k=k_start;
p_fit=polyfit(x,y,k);
res_even=sum((y-polyval(p_fit,x)).^2);
while k<k_end
n1=k;
k=k+1;
value1=0;
value2=0;
for i=-m:m
value1=value1+Pkmi_array(k+2,m,i+m+1)*y(i+m+1);
value2=value2+(Pkmi_array(k+2,m,i+m+1))^2;
end
res_tmp=res_even(end)-value1^2/value2;
k=k+1;
value1=0;
value2=0;
for i=-m:m
value1=value1+Pkmi_array(k+2,m,i+m+1)*y(i+m+1);
value2=value2+(Pkmi_array(k+2,m,i+m+1))^2;
end
res_even=[res_even res_tmp-value1^2/value2];
n2=k;
v1=n2-n1;
v2=N-n2-1;
Fx=(res_even(end-1)-res_even(end))/(n2-n1)/(res_even(end)+eps)*(N-n2-1);
F_alpha=finv(1-alpha,v1,v2);
if Fx<F_alpha
break;
end
end
if Fx<F_alpha
polynomial_degree=k-2;
else
polynomial_degree=k_end;
end
end
