Hi everyone, i analyzed ECG signal with wavelet transform.What is the relationship between the original signal and the coefficients of signal? WHY value of signal change?, (This question is very important to me)

[c,l]=wavedec(nfile,8,'db8'); ca1=appcoef(c,l,'db8',1); ca2=appcoef(c,l,'db8',2); ca3=appcoef(c,l,'db8',3); ca4=appcoef(c,l,'db8',4); figure(2),plot(ca1,'-k'),title('Cofficients of Signal At l Level Decomposition') figure(3),plot(ca2,'-k'),title('Cofficients of Signal At 2 Level Decomposition') figure(4),plot(ca3,'-k'),title('Cofficients of Signal At 3 Level Decomposition') figure(5),plot(ca4,'-r'),title('Cofficients of Signal At 4 Level Decomposition')