tomopy/tomopy

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//  ---------------------------------------------------------------
//   TOMOPY header

/** \file constants.hh
 * \headerfile constants.hh "include/constants.hh"
 * physical constants available to C++
 */

#pragma once

#include "macros.hh"

//======================================================================================//

#ifndef M_PI
#    define M_PI 3.14159265358979323846264338327
#endif

namespace
{
// pi numbers
constexpr float pi     = static_cast<float>(M_PI);
constexpr float halfpi = 0.5f * pi;
constexpr float twopi  = 2.0f * pi;
// 2 * the hardware epsilon for floating point numbers
constexpr float epsilonf = 2.0f * std::numeric_limits<float>::epsilon();
// convert radians to degrees: theta_in_radians * degrees
// convert degrees to radians: theta_in_degrees / degrees
constexpr float degrees = 180.0f / pi;
}

//======================================================================================//