% Power estimation on discrete signals
function [y,yf] = smhs(x,Nw1,Nw2,yi)

N = length(x);
y = zeros(1,N);
x = abs(x);

if (x(1) > yi) 
  y(1) = (1-1/Nw1)*yi + (1/Nw1)*x(1);
else
  y(1) = (1-1/Nw2)*yi + (1/Nw2)*x(1);
end;

for n = 2:N,
    if (x(n) > y(n-1)) 
      y(n) = (1-1/Nw1)*y(n-1) + (1/Nw1)*x(n);
    else
      y(n) = (1-1/Nw2)*y(n-1) + (1/Nw2)*x(n);
    end;
end;
yf = y(N);