IIR_Butterworth_C_Sharp 1.0.2

C# code to calculate the coefficients of the Butterworth filter

This code calculate the coefficients of the Band-pass, Band-stop, Low-pass and High-pass Butterworth filters.

Each filter function will return a 2 rows x N coefficients 2D vector, where Row 1 = Numerator and Row 2 = Denumerator. The method "Check_stability_iir" can be used to check the stability of the filter. Please, keep in mind that if the filter is unstable, numerical instability leading to numerical overflow might happen. If that situation occurs, the program might assign a default value of 10^10 at the denominator.

Band-pass: the method is "double[][] Lp2bp(double W_f1, double W_f2, int order_filt);". The first two arguments are the two cut-off frequencies and the last argument is the order;

Band-stop: the method is "double[][] Lp2bs(double W_f1, double W_f2, int order_filt)". The first two arguments are the two cut-off frequencies and the last argument is the order;

Low-pass: the method is "double[][] Lp2lp(double W_f2, int order_filt)". The first argument is the cut-off frequency and the last argument is the order;

High-pass: the method is "double[][] Lp2hp(double W_f1, int order_filt)". The first argument is the cut-off frequency and the last argument is the order;

Check the stability of the filter: the method is "bool Check_stability_iir(double[][] coeff_filt)". The argument is the 2D array containing the filter coefficients. It returns "true" if the filter is stable, "false" if it is unstable.

Filter the data: the method is "double[] Filter_Data(double[][] coeff_filt, double[] pre_filt_signal)". The two arguments are the filter coefficients and the signal to be filtered. It returns the filtered signal.