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/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
* Qwt Widget Library
* Copyright (C) 1997 Josef Wilgen
* Copyright (C) 2002 Uwe Rathmann
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the Qwt License, Version 1.0
*****************************************************************************/
#include "qwt_transform.h"
#include "qwt_math.h"
#if QT_VERSION < 0x040601
#define qExp(x) ::exp(x)
#endif
//! Smallest allowed value for logarithmic scales: 1.0e-150
const double QwtLogTransform::LogMin = 1.0e-150;
const double QwtLogTransform::LogMax = 1.0e150;
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//! Constructor
QwtTransform::QwtTransform()
{
}
//! Destructor
QwtTransform::~QwtTransform()
{
}
/*!
\param value Value to be bounded
\return value unmodified
*/
double QwtTransform::bounded( double value ) const
{
return value;
}
//! Constructor
QwtNullTransform::QwtNullTransform():
QwtTransform()
{
}
//! Destructor
QwtNullTransform::~QwtNullTransform()
{
}
/*!
\param value Value to be transformed
\return value unmodified
*/
double QwtNullTransform::transform( double value ) const
{
return value;
}
/*!
\param value Value to be transformed
\return value unmodified
*/
double QwtNullTransform::invTransform( double value ) const
{
return value;
}
//! \return Clone of the transformation
QwtTransform *QwtNullTransform::copy() const
{
return new QwtNullTransform();
}
//! Constructor
QwtLogTransform::QwtLogTransform():
QwtTransform()
{
}
//! Destructor
QwtLogTransform::~QwtLogTransform()
{
}
/*!
\param value Value to be transformed
\return log( value )
*/
double QwtLogTransform::transform( double value ) const
{
return ::log( value );
}
/*!
\param value Value to be transformed
\return exp( value )
*/
double QwtLogTransform::invTransform( double value ) const
{
return qExp( value );
}
/*!
\param value Value to be bounded
\return qBound( LogMin, value, LogMax )
*/
double QwtLogTransform::bounded( double value ) const
{
return qBound( LogMin, value, LogMax );
}
//! \return Clone of the transformation
QwtTransform *QwtLogTransform::copy() const
{
return new QwtLogTransform();
}
/*!
Constructor
\param exponent Exponent
*/
QwtPowerTransform::QwtPowerTransform( double exponent ):
QwtTransform(),
d_exponent( exponent )
{
}
//! Destructor
QwtPowerTransform::~QwtPowerTransform()
{
}
/*!
\param value Value to be transformed
\return Exponentiation preserving the sign
*/
double QwtPowerTransform::transform( double value ) const
{
if ( value < 0.0 )
return -qPow( -value, 1.0 / d_exponent );
else
return qPow( value, 1.0 / d_exponent );
}
/*!
\param value Value to be transformed
\return Inverse exponentiation preserving the sign
*/
double QwtPowerTransform::invTransform( double value ) const
{
if ( value < 0.0 )
return -qPow( -value, d_exponent );
else
return qPow( value, d_exponent );
}
//! \return Clone of the transformation
QwtTransform *QwtPowerTransform::copy() const
{
return new QwtPowerTransform( d_exponent );
}