qwt_transform.cpp

/******************************************************************************
 * 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"
 
const double QwtLogTransform::LogMin = 1.0e-150;
 
const double QwtLogTransform::LogMax = 1.0e150;
 
QwtTransform::QwtTransform()
{
}
 
QwtTransform::~QwtTransform()
{
}
 
double QwtTransform::bounded( double value ) const
{
    return value;
}
 
QwtNullTransform::QwtNullTransform():
    QwtTransform()
{
}
 
QwtNullTransform::~QwtNullTransform()
{
}
 
double QwtNullTransform::transform( double value ) const
{
    return value;
}
 
double QwtNullTransform::invTransform( double value ) const
{
    return value;
}
 
QwtTransform* QwtNullTransform::copy() const
{
    return new QwtNullTransform();
}
 
QwtLogTransform::QwtLogTransform():
    QwtTransform()
{
}
 
QwtLogTransform::~QwtLogTransform()
{
}
 
double QwtLogTransform::transform( double value ) const
{
    return std::log( value );
}
 
double QwtLogTransform::invTransform( double value ) const
{
    return std::exp( value );
}
 
double QwtLogTransform::bounded( double value ) const
{
    return qBound( LogMin, value, LogMax );
}
 
QwtTransform* QwtLogTransform::copy() const
{
    return new QwtLogTransform();
}
 
QwtPowerTransform::QwtPowerTransform( double exponent ):
    QwtTransform(),
    m_exponent( exponent )
{
}
 
QwtPowerTransform::~QwtPowerTransform()
{
}
 
double QwtPowerTransform::transform( double value ) const
{
    if ( value < 0.0 )
        return -std::pow( -value, 1.0 / m_exponent );
    else
        return std::pow( value, 1.0 / m_exponent );
 
}
 
double QwtPowerTransform::invTransform( double value ) const
{
    if ( value < 0.0 )
        return -std::pow( -value, m_exponent );
    else
        return std::pow( value, m_exponent );
}
 
QwtTransform* QwtPowerTransform::copy() const
{
    return new QwtPowerTransform( m_exponent );
}