![]() Function Summary > IIR |
Performs Infinite Impulse Response digital filtering on supplied vector. This function performs the operation:
y_n = x_n c_0 + y_{n-1}c_1 + y_{n-2}c_2 \dotswhere:
x | is the input vector (argument 1) |
c | is the coefficient vector (argument 2) |
y | is the result (returned value) |
The operation of this function (and also the function FIR ) is simple but its application can be the subject of several volumes! In principle an almost unlimited range of IIR filtering operations may be performed using this function. Any text on Digital Signal Processing will provide further details.
User's should note that using this function applied to raw transient analysis data will not produce meaningful results as the values are unevenly spaced. If you apply this function to simulation data, you must either specify that the simulator outputs at fixed intervals (select the Output at .PRINT step option in the Interp.
dialog box) or you must interpolate the results using the functionNumber | Type | Compulsory | Default | Description |
---|---|---|---|---|
1 |
real array |
Yes |
|
Vector to be filtered |
2 |
real array |
Yes |
|
Coefficients |
3 |
real array |
No |
zero |
Initial conditions |
Return type: real array
The following graph shows the result of applying a simple first order IIR filter to a step:
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