/*!
 * Copyright 2014 by Contributors
 * \file math.h
 * \brief support additional math
 * \author Tianqi Chen
 */
#ifndef XGBOOST_UTILS_MATH_H_
#define XGBOOST_UTILS_MATH_H_

#include <cmath>

namespace xgboost {
namespace utils {
#ifdef XGBOOST_STRICT_CXX98_
// check nan
bool CheckNAN(double v);
double LogGamma(double v);
#else
template<typename T>
inline bool CheckNAN(T v) {
#ifdef _MSC_VER
  return (_isnan(v) != 0);
#else
  return isnan(v);
#endif
}
template<typename T>
inline T LogGamma(T v) {
#ifdef _MSC_VER
#if _MSC_VER >= 1800
  return lgamma(v);
#else
#pragma message("Warning: lgamma function was not available until VS2013"\
                ", poisson regression will be disabled")
  utils::Error("lgamma function was not available until VS2013");
  return static_cast<T>(1.0);
#endif
#else
  return lgamma(v);
#endif
}
#endif
}  // namespace utils
}  // namespace xgboost
#endif  // XGBOOST_UTILS_MATH_H_