Graph filter poles and zeros on the Z-plane The zplane~ object provides a way to graph filter poles and zeros in the Z-plane for display. Use the zplane~ object in conjunction with the filtergraph~ object, or provide it with a list of biquad~ coefficients. Cycling '74 MSP MSP U/I Filter coefficient a0 TEXT_HERE Filter coefficient a1 TEXT_HERE Filter coefficient a2 TEXT_HERE Filter coefficient b1 TEXT_HERE Filter coefficient b2 TEXT_HERE List of 2nd Order Filter Coefficients TEXT_HERE List of Zero Coordinate Pairs TEXT_HERE List of Pole Coordinate Pairs TEXT_HERE List of 2nd Order Filter Gains TEXT_HERE TEXT_HERE TEXT_HERE Output the current pole and zero values Causes the current pole and zero values to be re-output. Function depends on inlet In 1st-5th inlets: A float in one of the first five inlets changes the current value of the corresponding biquad~ filter coefficients (a0, a1, a2, b1, and b2, respectively), recalculates and displays the filter's pole-zero graph on the Z-plane and causes a lists of poles and zeros be output. Set filter coefficients, display poles/zeros, and output pole/zero data In left inlet: A list of five float values which correspond to biquad~ filter coefficients sets the zplane~ object's internal values for these coefficients and causes the object to visually display the poles and zeros for the filter(s) and to output the pole and zero data.

If more than five values are sent, they are interpreted as sets of cascaded biquad coefficients. The zplane~ object will display a composite pole-zero graph which shows the multiplication of a group of biquad filters in cascade. Up to 24 groups of five float values may be cascaded. Use a filterdesign dictionary's filter coefficients The word dictionary, followed by a symbol that references a named filterdesign object dictionary (set via the name attribute), will cause the zplane~ object to use the dictionary values for filter coefficients. Set filter coefficient a1 In 2nd inlet: Sets the current value of the biquad~ filter's a1 coefficient. Set filter coefficient a2 In 3rd inlet: Sets the current value of the biquad~ filter's a2 coefficient. Set filter coefficient b1 In 4th inlet: Sets the current value of the biquad~ filter's b1 coefficient. Set filter coefficient b2 In 5th inlet: Sets the current value of the biquad~ filter's b2 coefficient. Change filter parameters by clicking and dragging in the zplane~ object’s display You can change the filter parameters by clicking and dragging on the zplane~ object’s display. Clicking and dragging on any of the poles (shown as an x in the display) or zeros (shown as an o in the display) will modify the filter coefficients and output the new filter coefficient values. Select linear or log frequency display The word logscale, followed by a zero or one, toggles between linear (the default) and log frequency display. Change the visual scaling of the object's display The word range, followed by a floating point value, changes the visual scaling of the zplane~ object's display. The default is 1.5. TEXT_HERE TEXT_HERE Background color Sets the background color of the zplane~ object in RGBA format. TEXT_HERE TEXT_HERE TEXT_HERE TEXT_HERE TEXT_HERE TEXT_HERE Grid Color Sets the colors for the grids and lines in RGBA format. The gridlinecolor attribute is mapped to the elementcolor style color. TEXT_HERE TEXT_HERE Number of Poles and Zeros The word order, followed by an even number between 2 and 24, sets the number of poles and zeros. Constrain poles to unit circle When set to 1, poles will be constrained inside the unit circle, and thus yield a stable filter. An argument of zero will turn this feature off (the default). Color Sets the pole zero color in RGBA format. The polezerocolor attribute is mapped to the color style color. TEXT_HERE TEXT_HERE Style Sets the style to be applied to the object. Styles can be set using the Format palette. Like the filtergraph~ object, it does not process audio signals by itself, but it does react internally to the current MSP sampling rate. The zplane~ object is designed to help in digital filter design and visualization for MSP, and to provide a basic pedagogical tool which may be used to help explain digital filter theory.
You can change the filter parameters by clicking and dragging on the zplane~ object’s display. Clicking and dragging on any of the poles (shown as an x in the display) or zeros (shown as an o in the display) will modify the filter coefficients and output the new filter coefficient values. Out left outlet: a list of 5 floating-point filter coefficients for the biquad~ object. Coefficients output in response to mouse clicks and changes in the coefficient inlets.

Out second outlet: a list of "zero" location values expressed as complex numbers (real, imaginary). These correspond to the "a" coefficients of the filter. A 2nd order (biquad) filter will have 2 zeros, a 4th order filter will have four, etc...

Out third outlet: a list of "pole" location values expressed as complex numbers (real, imaginary). These correspond to the "b" coefficients of the filter. A 2nd order (biquad) filter will have 2 zeros, a 4th order filter will have four, etc...

Out fourth outlet: a list of floating-point values representing the overall gain of each cascaded filter.