Overload List
Overload 1: Double ChebyshevIIFilter(Int32 Order, Double StopRipple, Double[] CutoffFreq, TFilterType FilterType, Boolean Analog, TMtx A, TVec B, TVec C, ref Double d)
The resulting transfer function is returned in the state-space form with A,B,C,D variables.
| # | Name | Type | Description |
|---|---|---|---|
| 1 | Order | Int32 | |
| 2 | StopRipple | Double | scalar |
| 3 | CutoffFreq | Double[] | |
| 4 | FilterType | TFilterType | |
| 5 | Analog | Boolean | |
| 6 | A | TMtx | source TMtx |
| 7 | B | TVec | source TVec |
| 8 | C | TVec | source TVec |
| 9 | d | Double (ref) | output |
Returns: Double
using Dew.Math;
using Dew.Math.Editors;
using Dew.Math.Units;
using Dew.Signal;
using Dew.Signal.Units;
using Dew.Math.Tee;
using Dew.Signal.Tee;
private void button1_Click(object sender, EventArgs e)
{
Vector z = new Vector(0);
Vector p = new Vector(0);
Vector num = new Vector(0);
Vector den = new Vector(0);
Vector Response = new Vector(0);
double[] WcArray = new double[1];
int Order;
Order = IIRFilters.ChebyshevIIOrder(new double[2] { 10.0*2/30, 12.0*2/30 }, 0.2, 50, TFilterType.ftHighpass, ref WcArray, false); //design analog protype
IIRFilters.ChebyshevIIFilter(Order, 50, WcArray, TFilterType.ftHighpass, false, num, den, TIirFrequencyTransform.ftStateSpaceAnalog);
SignalUtils.FrequencyResponse(num, den, Response, 32, false, TSignalWindowType.wtRectangular, 0);
Vector FreqFr = MtxExpr.Ramp(Response.Length, mvDouble,0, 1.0 / Response.Length); //X axis
DrawIt(FreqFr,20*MtxExpr.Log10(MtxExpr.Abs(Response)),"Magnitude",false);
}Overload 2: Double ChebyshevIIFilter(Int32 Order, Double StopRipple, Double[] CutoffFreq, TFilterType FilterType, Boolean Analog, TVec Num, TVec Den, TIirFrequencyTransform IirFrequencyTransform)
The resulting transfer function is returned in the numerator/denumerator form with num and den.
| # | Name | Type | Description |
|---|---|---|---|
| 1 | Order | Int32 | |
| 2 | StopRipple | Double | scalar |
| 3 | CutoffFreq | Double[] | |
| 4 | FilterType | TFilterType | |
| 5 | Analog | Boolean | |
| 6 | Num | TVec | source TVec |
| 7 | Den | TVec | source TVec |
| 8 | IirFrequencyTransform | TIirFrequencyTransform |
Returns: Double
Overload 3: Double ChebyshevIIFilter(Int32 Order, Double StopRipple, Double[] CutoffFreq, TFilterType FilterType, Boolean Analog, TVec z, TVec p, ref Double k, TIirFrequencyTransform IirFrequencyTransform)
Design Chebyshev type II IIR filter.
| # | Name | Type | Description |
|---|---|---|---|
| 1 | Order | Int32 | |
| 2 | StopRipple | Double | scalar |
| 3 | CutoffFreq | Double[] | |
| 4 | FilterType | TFilterType | |
| 5 | Analog | Boolean | |
| 6 | z | TVec | source TVec |
| 7 | p | TVec | source TVec |
| 8 | k | Double (ref) | output |
| 9 | IirFrequencyTransform | TIirFrequencyTransform |
Returns: Double
Design Chebyshev type II filter of Order with CutoffFreq frequencies and of FilterType type. Set Analog to True, to request an analog filter design in s-plane or set it to false to obtain a digital filter design in z-plane. StopRipple defines the stopband ripple in dB. CutoffFreq must be in range between 0 and 1 (Sampling frequency = 2) in case of a digital filter design.
IirFrequencyTransform specifies when and how will the frequency band transformation be applied. The resulting transfer function is returned in the zero-pole form, with z,p,k variables.
Overload 4: Double ChebyshevIIFilter(Int32 Order, Double StopRipple, Double[] CutoffFreq, TFilterType FilterType, Boolean Analog, TVec sos, TIirFrequencyTransform IirFrequencyTransform)
The resulting transfer function is returned in the second order section form stored in the sos variable.
| # | Name | Type | Description |
|---|---|---|---|
| 1 | Order | Int32 | |
| 2 | StopRipple | Double | scalar |
| 3 | CutoffFreq | Double[] | |
| 4 | FilterType | TFilterType | |
| 5 | Analog | Boolean | |
| 6 | sos | TVec | source TVec |
| 7 | IirFrequencyTransform | TIirFrequencyTransform |
Returns: Double
The sos variable can be passed directly to the IirInitBQ digital filter initialization routine. Second order section form delivers substantially higher numerical stability and range than filtering with num/den form which is used by the IirInit routine.