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BiQuad Class Reference

STK biquad (two-pole, two-zero) filter class. More...

#include <BiQuad.h>

Inheritance diagram for BiQuad::

Filter Stk FormSwep List of all members.

Public Methods

 BiQuad ()
 Default constructor creates a second-order pass-through filter.

virtual ~BiQuad ()
 Class destructor.

void clear (void)
 Clears all internal states of the filter.

void setB0 (MY_FLOAT b0)
 Set the b[0] coefficient value.

void setB1 (MY_FLOAT b1)
 Set the b[1] coefficient value.

void setB2 (MY_FLOAT b2)
 Set the b[2] coefficient value.

void setA1 (MY_FLOAT a1)
 Set the a[1] coefficient value.

void setA2 (MY_FLOAT a2)
 Set the a[2] coefficient value.

void setResonance (MY_FLOAT frequency, MY_FLOAT radius, bool normalize=FALSE)
 Sets the filter coefficients for a resonance at frequency (in Hz). More...

void setNotch (MY_FLOAT frequency, MY_FLOAT radius)
 Set the filter coefficients for a notch at frequency (in Hz). More...

void setEqualGainZeroes ()
 Sets the filter zeroes for equal resonance gain. More...

void setGain (MY_FLOAT theGain)
 Set the filter gain. More...

MY_FLOAT getGain (void) const
 Return the current filter gain.

MY_FLOAT lastOut (void) const
 Return the last computed output value.

MY_FLOAT tick (MY_FLOAT sample)
 Input one sample to the filter and return one output.

MY_FLOAT* tick (MY_FLOAT *vector, unsigned int vectorSize)
 Input vectorSize samples to the filter and return an equal number of outputs in vector.

Detailed Description

STK biquad (two-pole, two-zero) filter class.

This protected Filter subclass implements a two-pole, two-zero digital filter. A method is provided for creating a resonance in the frequency response while maintaining a constant filter gain.

by Perry R. Cook and Gary P. Scavone, 1995 - 2002.

Member Function Documentation

void BiQuad::setResonance ( MY_FLOAT frequency,
MY_FLOAT radius,
bool normalize = FALSE )
 

Sets the filter coefficients for a resonance at frequency (in Hz).

This method determines the filter coefficients corresponding to two complex-conjugate poles with the given frequency (in Hz) and radius from the z-plane origin. If normalize is true, the filter zeros are placed at z = 1, z = -1, and the coefficients are then normalized to produce a constant unity peak gain (independent of the filter gain parameter). The resulting filter frequency response has a resonance at the given frequency. The closer the poles are to the unit-circle (radius close to one), the narrower the resulting resonance width.

void BiQuad::setNotch ( MY_FLOAT frequency,
MY_FLOAT radius )
 

Set the filter coefficients for a notch at frequency (in Hz).

This method determines the filter coefficients corresponding to two complex-conjugate zeros with the given frequency (in Hz) and radius from the z-plane origin. No filter normalization is attempted.

void BiQuad::setEqualGainZeroes ( )
 

Sets the filter zeroes for equal resonance gain.

When using the filter as a resonator, zeroes places at z = 1, z = -1 will result in a constant gain at resonance of 1 / (1 - R), where R is the pole radius setting.

void BiQuad::setGain ( MY_FLOAT theGain ) [virtual]
 

Set the filter gain.

The gain is applied at the filter input and does not affect the coefficient values. The default gain value is 1.0.

Reimplemented from Filter.

The documentation for this class was generated from the following file:
The Synthesis ToolKit in C++ (STK)
©1995-2002 Perry R. Cook and Gary P. Scavone. All Rights Reserved.