File: mathFuncs.h

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/**
 * \file        mathFuncs.h
 * \brief       Mathematical functions.
 * \copyright   Copyright (C) 2006-2022 Ralf Hoppe <ralf.hoppe@dfcgen.de>
 */

#ifndef MATHFUNCS_H
#define MATHFUNCS_H


/* INCLUDE FILES **************************************************************/

#include "base.h"               /* includes config.h (include before math.h)  */

#include <math.h>

#include <gsl/gsl_math.h>
#include <gsl/gsl_sf.h>                              /* all special functions */
#include <gsl/gsl_errno.h>


#ifdef  __cplusplus
extern "C" {
#endif


/* GLOBAL TYPE DECLARATIONS ***************************************************/


/** Decimal normalized double value. The original value is determined by
 *  \f$m 10^e\f$.
 */
typedef struct
{
    double mantissa;                                          /**< mantissa m */
    double exponent;                                          /**< exponent e */
} MATH_NORMDBL;




/* GLOBAL CONSTANT DECLARATIONS ***********************************************/


/* GLOBAL VARIABLE DECLARATIONS ***********************************************/


/* GLOBAL MACRO DEFINITIONS ***************************************************/


/** This macro swaps two integers (inline).
 */
#define MATH_SWAP_INT(int1, int2)                               \
{                                                               \
    (int1) ^= (int2);                                           \
    (int2) ^= (int1);                                           \
    (int1) ^= (int2);                                           \
}




#ifdef HAVE_HYPOT
#define HYPOT(x, y) hypot ((x), (y))
#else
#define HYPOT(x, y) gsl_hypot ((x), (y))
#endif


#ifdef HAVE_POW10                                         /* pow10() exists? */
#define POW10(x) pow10(x)
#else
#ifdef HAVE_EXP10
#define POW10(x) exp10(x)       /**< 10 raised to \p x, means \f$y=10^{x}\f$ */
#else
#define POW10(x) pow(10, (x))         /* fallback to (slow) generic function */
#endif /* HAVE_EXP10 */
#endif /* HAVE_POW10 */


#ifndef HAVE_TRUNC
#define trunc(x)           ((GSL_SIGN(x) > 0) ? floor(x) : ceil(x))
#endif


#ifndef HAVE_ROUND
#define round(x)           floor((x) + 0.5)     /* fallback to (slow) generic */
#endif




/* EXPORTED FUNCTIONS *********************************************************/



/* FUNCTION *******************************************************************/
/** Calculates a normalized value consisting of (decimal) mantissa and exponent.
 *
 *  \param val          Value to be converted.
 *
 *  \return             Normalized value.
 ******************************************************************************/
    MATH_NORMDBL mathNorm10(double val);



/* FUNCTION *******************************************************************/
/** Denormalizes a decimal value from its mantissa and exponent.
 *
 *  \param val          Normalized value to be converted.
 *
 *  \return             Denormalized value.
 ******************************************************************************/
    double mathDenorm10(MATH_NORMDBL val);



/* FUNCTION *******************************************************************/
/** Rectangle function
    \f[
       y = \begin{cases} 0, & \mbox{if} \;\; x<0 \\
                         0, & \mbox{if} \;\; x>1 \\
                         1, & \mbox{else} \end{cases}
    \f]
 *
 *  \param x            Argument \f$x\f$.
 *
 *  \return             Result \f$y\f$.
 ******************************************************************************/
    double mathFuncRectangle (double x);


/* FUNCTION *******************************************************************/
/** \e Hamming window function
    \f[
       y = \begin{cases} 0, & \mbox{if} \;\; x<0 \\
                         0, & \mbox{if} \;\; x>1 \\
                         0.54-0.46 \cos(2\pi x), & \mbox{else} \end{cases}
    \f]
 *
 *  \param x            Argument \f$x\f$.
 *
 *  \return             Result \f$y\f$.
 ******************************************************************************/
    double mathFuncHamming (double x);



/* FUNCTION *******************************************************************/
/** \e van \e Hann window function
    \f[
       y = \begin{cases} 0, & \mbox{if} \;\; x<0 \\
                         0, & \mbox{if} \;\; x>1 \\
                         \frac{1}{2}\,[1-\cos(2\pi x)], & \mbox{else} \end{cases}
    \f]
 *
 *  \param x            Argument \f$x\f$.
 *
 *  \return             Result \f$y\f$.
 ******************************************************************************/
    double mathFuncVanHann (double x);



/* FUNCTION *******************************************************************/
/** \e Blackman window function
    \f[
       y = \begin{cases} 0, & \mbox{if} \;\; x<0 \\
                         0, & \mbox{if} \;\; x>1 \\
                         0.42-0.5\cos(2\pi x)+0.08\cos(4\pi x), & \mbox{else}
           \end{cases}
    \f]
 *
 *  \param x            Argument \f$x\f$.
 *
 *  \return             Result \f$y\f$.
 ******************************************************************************/
    double mathFuncBlackman (double x);



/* FUNCTION *******************************************************************/
/** \e Kaiser window function
    \f[
       y = \begin{cases} 0, & \mbox{if} \;\; x<0 \\
                         0, & \mbox{if} \;\; x>1 \\
                         \frac{I_0\left(\alpha\sqrt{1-(2 x-1)^2}\right)}
                              {I_0(\alpha)}, & \mbox{else}
           \end{cases}
    \f]
 *
 *  \param x            Argument \f$x\f$.
 *  \param alpha        Parameter \f$\alpha\f$.
 *
 *  \return             Result \f$y\f$ when successful evaluated, else
 *                      GSL_POSINF or GSL_NEGINF. Use the functions gsl_isinf()
 *                      or gsl_finite() for result checking.
 ******************************************************************************/
   double mathFuncKaiser (double x, double alpha);


#ifdef  __cplusplus
}
#endif


#endif /* MATHFUNCS_H */


/******************************************************************************/
/* END OF FILE                                                                */
/******************************************************************************/