Help me understanding the super equalizer source code
result[i] =
band_gain[0] * LPF(t, band_freq[0]) +
band_gain[1] * (LPF(t, band_freq[1]) - LPF(a, band_freq[0])) +
band_gain[2] * (LPF(t, band_freq[2]) - LPF(a, band_freq[1])) +
band_gain[3] * (LPF(t, band_freq[3]) - LPF(a, band_freq[2])) +
band_gain[4] * (IMPULSE(t) - LPF(t, band_freq[3]));


is actually very simple to explain with pictures. First we assume f0 &lt; f1 &lt; f2 &lt; f3.... lets look at one section

band_gain[0] * LPF(t, band_freq[0]) means create a low pass filter with cutoff frequency band_freq[0] it then says to multiply the amplitude of the filter by band_gain[0] something like this


now lets move onto the more complicated lines

band_gain[1] * (LPF(t, band_freq[1]) - LPF(a, band_freq[0])) means make a LPF with Cutoff band_freq[1] then subtract from it a LPF with cutoff band_freq[0] if you look at the image below thats the pink section. Then you multiply the result by `band_gain1'
 

you can find the other bands in a similar fashion . Now lets add them together, something like this, just 'superposition'


which makes our final filter look roughly like this


I hope those pictures make sense