This is matlab session for signal compression. Here using Quantize function. can you help me to answer how the function works? and why using quantize function?

function y = quantize (x, bits) m = max (abs (x)); delta_step=m/24 (bits-1); y=quant (x, delta_step); y(y == * -(2^ (bits-1) *delta_step)) = -(2^(bits-1)-1) *delta_step; function y = quantize (x, bits) m = max (abs (x)); delta_step=m/24 (bits-1); y=quant (x, delta_step); y(y == * -(2^ (bits-1) *delta_step)) = -(2^(bits-1)-1) *delta_step