hi guys Im on a music tec course at uni and im playing with some DSP. Ive been able to successfuly create some simple code for low and high pass filters where you just input a center frequency but now im trying to further that by adding a q variable also. The equations for the coefficents are highlighted in red. Ino the rest of the code works as it should because when i just change the coeficents values depending on the filter it works. But when i change them to these it plays no sound and the variable y which is my output doesnt contain any samples. In a nut shell the equations in the text book what am i doing wrong to translate them into my code? thanks guys hope im making sense On a side note before you think it im not asking you to do any work for me, this is further reading.