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QwtLogTransform(3) Qwt User's Guide QwtLogTransform(3)

NAME

QwtLogTransform - Logarithmic transformation.

SYNOPSIS

#include <qwt_transform.h>

Inherits QwtTransform.

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 QwtTransform * copy () const

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:
value Value 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:
value Value to be transformed

Returns:

exp( value )

Implements QwtTransform.

double QwtLogTransform::transform (double value) const [virtual]

Parameters:
value Value to be transformed

Returns:

log( value )

Implements QwtTransform.

Author

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Wed Jan 2 2019 Version 6.1.4