Overload List
Overload 1: Double EllipticFilter(Int32 Order, Double PassRipple, 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 | PassRipple | Double | scalar |
| 3 | StopRipple | Double | scalar |
| 4 | CutoffFreq | Double[] | |
| 5 | FilterType | TFilterType | |
| 6 | Analog | Boolean | |
| 7 | A | TMtx | source TMtx |
| 8 | B | TVec | source TVec |
| 9 | C | TVec | source TVec |
| 10 | 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; //design a fifth order filter.
Order = IIRFilters.EllipticOrder(new double[2] { 5.0/15, 6.0/15 }, 0.1, 40, TFilterType.ftLowpass, ref WcArray, false); //design analog protype
IIRFilters.EllipticFilter(Order, 0.1,40, WcArray, TFilterType.ftLowpass, false, num, den, TIirFrequencyTransform.ftStateSpaceAnalog);
SignalUtils.FrequencyResponse(num, den, Response, 32, false, TSignalWindowType.wtRectangular, 0);
Vector FreqFr = MtxExpr.Ramp(Response.Length, TMtxFloatPrecision.mvDouble,0, 30*0.5 / Response.Length); //X axis
MtxVecTee.DrawIt(FreqFr, Response, "Frequency response", false);
}Overload 2: Double EllipticFilter(Int32 Order, Double PassRipple, 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 | PassRipple | Double | scalar |
| 3 | StopRipple | Double | scalar |
| 4 | CutoffFreq | Double[] | |
| 5 | FilterType | TFilterType | |
| 6 | Analog | Boolean | |
| 7 | Num | TVec | source TVec |
| 8 | Den | TVec | source TVec |
| 9 | IirFrequencyTransform | TIirFrequencyTransform |
Returns: Double
Overload 3: Double EllipticFilter(Int32 Order, Double PassRipple, Double StopRipple, Double[] CutoffFreq, TFilterType FilterType, Boolean Analog, TVec z, TVec p, ref Double k, TIirFrequencyTransform IirFrequencyTransform)
Design Elliptic IIR filter.
| # | Name | Type | Description |
|---|---|---|---|
| 1 | Order | Int32 | |
| 2 | PassRipple | Double | scalar |
| 3 | StopRipple | Double | scalar |
| 4 | CutoffFreq | Double[] | |
| 5 | FilterType | TFilterType | |
| 6 | Analog | Boolean | |
| 7 | z | TVec | source TVec |
| 8 | p | TVec | source TVec |
| 9 | k | Double (ref) | output |
| 10 | IirFrequencyTransform | TIirFrequencyTransform |
Returns: Double
Design Elliptic 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. 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. PassRipple defines the passband ripple in dB and StopRipple defines the stopband ripple in dB. The resulting transfer function is returned in the zero-pole form, with z,p,k variables.
Overload 4: Double EllipticFilter(Int32 Order, Double PassRipple, 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 | PassRipple | Double | scalar |
| 3 | StopRipple | Double | scalar |
| 4 | CutoffFreq | Double[] | |
| 5 | FilterType | TFilterType | |
| 6 | Analog | Boolean | |
| 7 | sos | TVec | source TVec |
| 8 | 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 used by the IirInit function.