Qwt User's Guide  6.1.3
QwtLogTransform Class Reference

Logarithmic transformation. More...

#include <qwt_transform.h>

Inheritance diagram for QwtLogTransform:

Public Member Functions

 QwtLogTransform ()
 Constructor.
 
virtual ~QwtLogTransform ()
 Destructor.
 
virtual double transform (double value) const
 
virtual double invTransform (double value) const
 
virtual double bounded (double value) const
 
virtual QwtTransformcopy () const
 
- Public Member Functions inherited from QwtTransform
 QwtTransform ()
 Constructor.
 
virtual ~QwtTransform ()
 Destructor.
 

Public Attributes

QT_STATIC_CONST double LogMin = 1.0e-150
 Smallest allowed value for logarithmic scales: 1.0e-150.
 
QT_STATIC_CONST double LogMax = 1.0e150
 Largest allowed value for logarithmic scales: 1.0e150.
 

Detailed Description

Logarithmic transformation.

QwtLogTransform modifies the values using log() and exp().

Note
In the calculations of QwtScaleMap the base of the log function has no effect on the mapping. So QwtLogTransform can be used for log2(), log10() or any other logarithmic scale.

Member Function Documentation

double QwtLogTransform::bounded ( double  value) const
virtual
Parameters
valueValue to be bounded
Returns
qBound( LogMin, value, LogMax )

Reimplemented from QwtTransform.

QwtTransform * QwtLogTransform::copy ( ) const
virtual
Returns
Clone of the transformation

Implements QwtTransform.

double QwtLogTransform::invTransform ( double  value) const
virtual
Parameters
valueValue to be transformed
Returns
exp( value )

Implements QwtTransform.

double QwtLogTransform::transform ( double  value) const
virtual
Parameters
valueValue to be transformed
Returns
log( value )

Implements QwtTransform.