qwt_math.h

/* -*- 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
 *****************************************************************************/

#ifndef QWT_MATH_H
#define QWT_MATH_H

#include <math.h> 
#include <qpoint.h>
#include "qwt_global.h"
#include "qwt_double_rect.h"

#if QT_VERSION < 0x040000

#define qwtMax QMAX
#define qwtMin QMIN
#define qwtAbs QABS

#else // QT_VERSION >= 0x040000

#define qwtMax qMax
#define qwtMin qMin
#define qwtAbs qAbs

#endif

#ifndef LOG10_2
#define LOG10_2     0.30102999566398119802  /* log10(2) */
#endif

#ifndef LOG10_3
#define LOG10_3     0.47712125471966243540  /* log10(3) */
#endif

#ifndef LOG10_5
#define LOG10_5     0.69897000433601885749  /* log10(5) */
#endif

#ifndef M_2PI
#define M_2PI       6.28318530717958623200  /* 2 pi */
#endif

#ifndef LOG_MIN
//! Mininum value for logarithmic scales
#define LOG_MIN 1.0e-100
#endif

#ifndef LOG_MAX
//! Maximum value for logarithmic scales
#define LOG_MAX 1.0e100
#endif

#ifndef M_E
#define M_E            2.7182818284590452354   /* e */
#endif

#ifndef M_LOG2E
#define M_LOG2E 1.4426950408889634074   /* log_2 e */
#endif

#ifndef M_LOG10E
#define M_LOG10E    0.43429448190325182765  /* log_10 e */
#endif

#ifndef M_LN2
#define M_LN2       0.69314718055994530942  /* log_e 2 */
#endif

#ifndef M_LN10
#define M_LN10         2.30258509299404568402  /* log_e 10 */
#endif

#ifndef M_PI
#define M_PI        3.14159265358979323846  /* pi */
#endif

#ifndef M_PI_2
#define M_PI_2      1.57079632679489661923  /* pi/2 */
#endif

#ifndef M_PI_4
#define M_PI_4      0.78539816339744830962  /* pi/4 */
#endif

#ifndef M_1_PI
#define M_1_PI      0.31830988618379067154  /* 1/pi */
#endif

#ifndef M_2_PI
#define M_2_PI      0.63661977236758134308  /* 2/pi */
#endif

#ifndef M_2_SQRTPI
#define M_2_SQRTPI  1.12837916709551257390  /* 2/sqrt(pi) */
#endif

#ifndef M_SQRT2
#define M_SQRT2 1.41421356237309504880  /* sqrt(2) */
#endif

#ifndef M_SQRT1_2
#define M_SQRT1_2   0.70710678118654752440  /* 1/sqrt(2) */
#endif

QWT_EXPORT double qwtGetMin(const double *array, int size);
QWT_EXPORT double qwtGetMax(const double *array, int size);


//! Return the sign 
inline int qwtSign(double x)
{
    if (x > 0.0)
       return 1;
    else if (x < 0.0)
       return (-1);
    else
       return 0;
}            

//! Return the square of a number
inline double qwtSqr(const double x)
{
    return x*x;
}

/*!
  \brief Limit a value to fit into a specified interval
  \param x Input value
  \param x1 First interval boundary
  \param x2 Second interval boundary  
*/
template <class T>
T qwtLim(const T& x, const T& x1, const T& x2)
{
    T rv;
    T xmin, xmax;
    
    xmin = qwtMin(x1, x2);
    xmax = qwtMax(x1, x2);

    if ( x < xmin )
       rv = xmin;
    else if ( x > xmax )
       rv = xmax;
    else
       rv = x;

    return rv;
}

inline QPoint qwtPolar2Pos(const QPoint &pole,
    double radius, double angle)
{
    const double x = pole.x() + radius * ::cos(angle);
    const double y = pole.y() - radius * ::sin(angle);

    return QPoint(qRound(x), qRound(y));
}

inline QPoint qwtDegree2Pos(const QPoint &pole,
    double radius, double angle)
{
    return qwtPolar2Pos(pole, radius, angle / 180.0 * M_PI);
}

inline QwtDoublePoint qwtPolar2Pos(const QwtDoublePoint &pole,
    double radius, double angle)
{
    const double x = pole.x() + radius * ::cos(angle);
    const double y = pole.y() - radius * ::sin(angle);

    return QPoint(qRound(x), qRound(y));
}

inline QwtDoublePoint qwtDegree2Pos(const QwtDoublePoint &pole,
    double radius, double angle)
{
    return qwtPolar2Pos(pole, radius, angle / 180.0 * M_PI);
}

//! Rounding of doubles, like qRound for integers
inline double qwtRound(double value)
{
    return ::floor(value + 0.5); // MSVC has no ::round().
}

#endif