function y=seasint(x,T)
%
%   y=seasint(x,T)
%
%   seasonally integrate x
%
%  x = input data
%  T = period of season

nx=length(x);
np=floor(nx/T);
rx=rem(nx,T);
y=zeros(size(x));
for j=1:T
    index=[j:T:nx];
    y(index)=cumsum(x(index));
end