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# stk::OneZero Class Reference

STK one-zero filter class. More...

`#include <OneZero.h>`

Inheritance diagram for stk::OneZero:

List of all members.

## Public Member Functions
| OneZero (StkFloat theZero=-1.0)
| The default constructor creates a low-pass filter (zero at z = -1.0).
| ~OneZero ()
| Class destructor.
void | setB0 (StkFloat b0)
| Set the b[0] coefficient value.
void | setB1 (StkFloat b1)
| Set the b[1] coefficient value.
void | setCoefficients (StkFloat b0, StkFloat b1, bool clearState=false)
| Set all filter coefficients.
void | setZero (StkFloat theZero)
| Set the zero position in the z-plane.
StkFloat | lastOut (void) const
| Return the last computed output value.
StkFloat | tick (StkFloat input)
| Input one sample to the filter and return one output.
StkFrames & | tick (StkFrames &frames, unsigned int channel=0)
| Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs.
StkFrames & | tick (StkFrames &iFrames, StkFrames &oFrames, unsigned int iChannel=0, unsigned int oChannel=0)
| Take a channel of the `iFrames` object as inputs to the filter and write outputs to the `oFrames` object.

## Detailed Description

STK one-zero filter class.

This class implements a one-zero digital filter. A method is provided for setting the zero position along the real axis of the z-plane while maintaining a constant filter gain.

by Perry R. Cook and Gary P. Scavone, 1995-2012.

## Member Function Documentation

void stk::OneZero::setZero | ( | StkFloat | theZero | ) |

Set the zero position in the z-plane.

This method sets the zero position along the real-axis of the z-plane and normalizes the coefficients for a maximum gain of one. A positive zero value produces a high-pass filter, while a negative zero value produces a low-pass filter. This method does not affect the filter gain value.

StkFrames & stk::OneZero::tick | ( | StkFrames & | frames,
|  | unsigned int | channel = `0` |
| ) |  |  | `[inline, virtual]`

Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs.

The StkFrames argument reference is returned. The `channel` argument must be less than the number of channels in the StkFrames argument (the first channel is specified by 0). However, range checking is only performed if _STK_DEBUG_ is defined during compilation, in which case an out-of-range value will trigger an StkError exception.

Implements stk::Filter.

    00089 {
    00090 #if defined(_STK_DEBUG_)
    00091   if ( channel >= frames.channels() ) {
    00092     oStream_ << "OneZero::tick(): channel and StkFrames arguments are incompatible!";
    00093     handleError( StkError::FUNCTION_ARGUMENT );
    00094   }
    00095 #endif
    00096
    00097   StkFloat *samples = &frames[channel];
    00098   unsigned int hop = frames.channels();
    00099   for ( unsigned int i=0; i<frames.frames(); i++, samples += hop ) {
    00100     inputs_[0] = gain_ * *samples;
    00101     *samples = b_[1] * inputs_[1] + b_[0] * inputs_[0];
    00102     inputs_[1] = inputs_[0];
    00103   }
    00104
    00105   lastFrame_[0] = *(samples-hop);
    00106   return frames;
    00107 }

StkFrames & stk::OneZero::tick | ( | StkFrames & | iFrames,
|  | StkFrames & | oFrames,
|  | unsigned int | iChannel = `0`,
|  | unsigned int | oChannel = `0` |
| ) |  |  | `[inline]`

Take a channel of the `iFrames` object as inputs to the filter and write outputs to the `oFrames` object.

The `iFrames` object reference is returned. Each channel argument must be less than the number of channels in the corresponding StkFrames argument (the first channel is specified by 0). However, range checking is only performed if _STK_DEBUG_ is defined during compilation, in which case an out-of-range value will trigger an StkError exception.

    00110 {
    00111 #if defined(_STK_DEBUG_)
    00112   if ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) {
    00113     oStream_ << "OneZero::tick(): channel and StkFrames arguments are incompatible!";
    00114     handleError( StkError::FUNCTION_ARGUMENT );
    00115   }
    00116 #endif
    00117
    00118   StkFloat *iSamples = &iFrames[iChannel];
    00119   StkFloat *oSamples = &oFrames[oChannel];
    00120   unsigned int iHop = iFrames.channels(), oHop = oFrames.channels();
    00121   for ( unsigned int i=0; i<iFrames.frames(); i++, iSamples += iHop, oSamples += oHop ) {
    00122     inputs_[0] = gain_ * *iSamples;
    00123     *oSamples = b_[1] * inputs_[1] + b_[0] * inputs_[0];
    00124     inputs_[1] = inputs_[0];
    00125   }
    00126
    00127   lastFrame_[0] = *(oSamples-oHop);
    00128   return iFrames;
    00129 }

The documentation for this class was generated from the following file:

- OneZero.h

The Synthesis ToolKit in C++ (STK)
©1995-2012 Perry R. Cook and Gary P. Scavone. All Rights Reserved.