wfilters magnitude - why maxim value equals to sqrt(2)?

Hi there,

I am using wfilters function to check the transfer function of wavelet families. After trying the attached code (an example of Haar wavelet), I find all the magnitude with a maxim value of sqrt(2). May I ask what is the reason for this, please?

Thank you very much.

if true
  N = 1024;
  Fmax = 10; 
  [LoD,HiD] = wfilters('haar');
  HiDFT = fft(HiD,N);
  DF = Fmax*2/(N-1);
  f = 0:DF:Fmax;
  figure;
  plot(f,abs(HiDFT(1:N/2)),'linewidth',2);
  axis tight;
  title('Level 1 Filter Transfer Function');
  xlabel('Frequency');
  ylabel('Magnitude');
end