vpMath.cpp

/****************************************************************************
 *
 * This file is part of the ViSP software.
 * Copyright (C) 2005 - 2015 by Inria. All rights reserved.
 *
 * This software is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * ("GPL") version 2 as published by the Free Software Foundation.
 * See the file LICENSE.txt at the root directory of this source
 * distribution for additional information about the GNU GPL.
 *
 * For using ViSP with software that can not be combined with the GNU
 * GPL, please contact Inria about acquiring a ViSP Professional
 * Edition License.
 *
 * See http://visp.inria.fr for more information.
 *
 * This software was developed at:
 * Inria Rennes - Bretagne Atlantique
 * Campus Universitaire de Beaulieu
 * 35042 Rennes Cedex
 * France
 *
 * If you have questions regarding the use of this file, please contact
 * Inria at visp@inria.fr
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Description:
 * Simple mathematical function not available in the C math library (math.h).
 *
 * Authors:
 * Eric Marchand
 *
 *****************************************************************************/

#include <stdint.h>
#include <numeric>
#include <functional>
#include <visp3/core/vpMath.h>
#include <visp3/core/vpException.h>


#if defined(VISP_HAVE_FUNC__ISNAN)
#  include <float.h>
#endif

#if !(defined(VISP_HAVE_FUNC_ISNAN) || defined(VISP_HAVE_FUNC_STD_ISNAN)) || !(defined(VISP_HAVE_FUNC_ISINF) || defined(VISP_HAVE_FUNC_STD_ISINF))
#  if defined _MSC_VER || defined __BORLANDC__
typedef __int64 int64;
typedef unsigned __int64 uint64;
#  else
typedef int64_t int64;
typedef uint64_t uint64;
#  endif

#ifndef DOXYGEN_SHOULD_SKIP_THIS
typedef union Cv64suf
{
  int64 i;
  uint64 u;
  double f;
}
Cv64suf;
#endif
#endif

const double vpMath::ang_min_sinc = 1.0e-8;
const double vpMath::ang_min_mc = 2.5e-4;


bool vpMath::isNaN(const double value)
{
#if defined(VISP_HAVE_FUNC_ISNAN)
  return isnan(value);
#elif defined(VISP_HAVE_FUNC_STD_ISNAN)
  return std::isnan(value);
#elif defined(VISP_HAVE_FUNC__ISNAN)
  return (_isnan(value) != 0);
#else
  #if 0
    //This trick should work for any compiler which claims to use IEEE floating point.
    //Do not work with g++ and -ffast-math option.
    return (value != value);
  #else
    //Taken from OpenCV source code CvIsNan()
    Cv64suf ieee754;
    ieee754.f = value;
    return (((unsigned)(ieee754.u >> 32) & 0x7fffffff) +
           ((unsigned)ieee754.u != 0) > 0x7ff00000) != 0;
  #endif
#endif
}
bool vpMath::isInf(const double value)
{
#if defined(VISP_HAVE_FUNC_ISINF)
  return isinf(value);
#elif defined(VISP_HAVE_FUNC_STD_ISINF)
  return std::isinf(value);
#elif defined(VISP_HAVE_FUNC__FINITE)
  return !_finite(value);
#else
  //Taken from OpenCV source code CvIsInf()
  Cv64suf ieee754;
  ieee754.f = value;
  return ((unsigned)(ieee754.u >> 32) & 0x7fffffff) == 0x7ff00000 &&
         (unsigned)ieee754.u == 0;
#endif
}

double vpMath::mcosc(double cosx, double x)
{
  if (fabs(x) < ang_min_mc) return 0.5 ;
  else  return ((1.0-cosx)/x/x) ;
}

double vpMath::msinc(double sinx, double x)
{
  if (fabs(x) < ang_min_mc) return (1./6.0) ;
  else  return ((1.0-sinx/x)/x/x) ;
}

double vpMath::sinc(double x)
{
  if (fabs(x) < ang_min_sinc) return 1.0 ;
  else  return sin(x)/x ;
}
double vpMath::sinc(double sinx, double x)
{
  if (fabs(x) < ang_min_sinc) return 1.0 ;
  else  return (sinx/x) ;
}

double vpMath::getMean(const std::vector<double> &v)
{
  if(v.empty()) {
    throw vpException(vpException::notInitialized, "Empty vector !");
  }

  double sum = 0.0;
  size_t size = v.size();

  sum = std::accumulate(v.begin(), v.end(), 0.0);

  return sum / (double) size;
}

double vpMath::getMedian(const std::vector<double> &v) {
  if(v.empty()) {
    throw vpException(vpException::notInitialized, "Empty vector !");
  }

  double median = 0.0;
  std::vector<double> v_copy = v;
  size_t size = v_copy.size();

  if(size % 2 == 0) {
    sort(v_copy.begin(), v_copy.end());
    median = (v_copy[size / 2 - 1] + v_copy[size / 2]) / 2.0;
  } else {
    std::nth_element(v_copy.begin(), v_copy.begin() + (int) (size/2), v_copy.end());
    median = v_copy[size/2];
  }

  return median;
}

double vpMath::getStdev(const std::vector<double> &v, const bool useBesselCorrection) {
  if(v.empty()) {
    throw vpException(vpException::notInitialized, "Empty vector !");
  }

  double mean = getMean(v);

  std::vector<double> diff(v.size());
  std::transform(v.begin(), v.end(), diff.begin(),
     std::bind2nd(std::minus<double>(), mean));
  double sq_sum = std::inner_product(diff.begin(), diff.end(), diff.begin(), 0.0);
  double divisor = (double) v.size();
  if(useBesselCorrection && v.size() > 1) {
    divisor = divisor-1;
  }

  return std::sqrt(sq_sum / divisor);
}