text: #include "scalar_constants.hpp"
  
  namespace glm {
      template<typename T, qualifier Q>
      GLM_FUNC_QUALIFIER T angle(qua < T, Q >
      const& x) {
      if (
      abs(x
      .w) >
  
      cos_one_over_two<T>()
  
      ) {
      return
      asin(sqrt(x.x * x.x + x.y * x.y + x.z * x.z)
      ) * static_cast<T>(2);
  }
  
  return
  acos(x
  .w) * static_cast<T>(2);
  }
  
  template<typename T, qualifier Q>
  GLM_FUNC_QUALIFIER vec<3, T, Q> axis(qua < T, Q >
  const& x)
  {
  T const tmp1 = static_cast<T>(1) - x.w * x.w;
  if(tmp1 <= static_cast<T>(0))
  return vec<3, T, Q>(0, 0, 1);
  T const tmp2 = static_cast<T>(1) / sqrt(tmp1);
  return
  vec<3, T, Q>(x
  .
  x *tmp2, x
  .
  y *tmp2, x
  .
  z *tmp2
  );
  }
  
  template<typename T, qualifier Q>
  GLM_FUNC_QUALIFIER qua <T, Q> angleAxis(T const &angle, vec<3, T, Q> const &v) {
      T const a(angle);
      T const s = glm::sin(a * static_cast<T>(0.5));
  
      return qua<T, Q>(glm::cos(a * static_cast<T>(0.5)), v * s);
  }
  
  }//namespace glm
  