i got an IIR filter bu I have only the coefficients. now i'd like to be able to change the filter characteristics of the low pass filter (the "cutoff" frequency) but all i got are a and b coefficients. i'd like to be able to set a multiplier that will "scale" the filter by that amount. if i set the multiplier to 0.5 i'd like to filter the same but two times lower or two times slower (50 Hz cutoff instead of 100Hz)
is it possible ? Or is it a lost cause ? and with Matlab ?
thanks so much