[article Boost.Quaternions
    [quickbook 1.3]
    [copyright 2001-2003 Hubert Holin]
    [purpose Quaternions]
    [license
        Distributed under the Boost Software License, Version 1.0.
        (See accompanying file LICENSE_1_0.txt or copy at
        [@http://www.boost.org/LICENSE_1_0.txt http://www.boost.org/LICENSE_1_0.txt])
    ]
    [authors [Holin, Hubert]]
    [category math]
    [last-revision $Date: 2006-12-29 11:08:32 +0000 (Fri, 29 Dec 2006) $]
]

[def __R ['[*R]]]
[def __C ['[*C]]]
[def __H ['[*H]]]
[def __O ['[*O]]]
[def __R3 ['[*'''R<superscript>3</superscript>''']]]
[def __R4 ['[*'''R<superscript>4</superscript>''']]]
[def __quadrulple ('''&#x03B1;,&#x03B2;,&#x03B3;,&#x03B4;''')]
[def __quat_formula ['[^q = '''&#x03B1; + &#x03B2;i + &#x03B3;j + &#x03B4;k''']]]
[def __quat_complex_formula ['[^q = ('''&#x03B1; + &#x03B2;i) + (&#x03B3; + &#x03B4;i)j''' ]]]
[def __not_equal ['[^xy '''&#x2260;''' yx]]]

[def __asinh [link boost_quaternions.math_special_functions.asinh asinh]]
[def __acosh [link boost_quaternions.math_special_functions.acosh acosh]]
[def __atanh [link boost_quaternions.math_special_functions.atanh atanh]]
[def __sinc_pi [link boost_quaternions.math_special_functions.sinc_pi sinc_pi]]
[def __sinhc_pi [link boost_quaternions.math_special_functions.sinhc_pi sinhc_pi]]

[def __log1p [link boost_quaternions.math_special_functions.log1p log1p]]
[def __expm1 [link boost_quaternions.math_special_functions.expm1 expm1]]
[def __hypot [link boost_quaternions.math_special_functions.hypot hypot]]

This manual is also available in 
[@http:svn.boost.org/svn/boost/sandbox/pdf/math/release/quaternion.pdf 
printer friendly PDF format].


[section Quaternions]

[section Overview]

Quaternions are a relative of complex numbers.

Quaternions are in fact part of a small hierarchy of structures built 
upon the real numbers, which comprise only the set of real numbers 
(traditionally named __R), the set of complex numbers (traditionally named __C), 
the set of quaternions (traditionally named __H) and the set of octonions 
(traditionally named __O), which possess interesting mathematical properties 
(chief among which is the fact that they are ['division algebras], 
['i.e.] where the following property is true: if ['[^y]] is an element of that 
algebra and is [*not equal to zero], then ['[^yx = yx']], where ['[^x]] and ['[^x']] 
denote elements of that algebra, implies that ['[^x = x']]). 
Each member of the hierarchy is a super-set of the former.

One of the most important aspects of quaternions is that they provide an 
efficient way to parameterize rotations in __R3 (the usual three-dimensional space) 
and __R4.

In practical terms, a quaternion is simply a quadruple of real numbers __quadrulple, 
which we can write in the form __quat_formula, where ['[^i]] is the same object as for complex numbers, 
and ['[^j]] and ['[^k]] are distinct objects which play essentially the same kind of role as ['[^i]].

An addition and a multiplication is defined on the set of quaternions, 
which generalize their real and complex counterparts. The main novelty 
here is that [*the multiplication is not commutative] (i.e. there are 
quaternions ['[^x]] and ['[^y]] such that __not_equal). A good mnemotechnical way of remembering 
things is by using the formula ['[^i*i = j*j = k*k = -1]].

Quaternions (and their kin) are described in far more details in this 
other [@../../../quaternion/TQE.pdf document] 
(with [@../../../quaternion/TQE_EA.pdf errata and addenda]).

Some traditional constructs, such as the exponential, carry over without 
too much change into the realms of quaternions, but other, such as taking 
a square root, do not.

[endsect]

[section Header File]

The interface and implementation are both supplied by the header file 
[@../../../../../boost/math/quaternion.hpp quaternion.hpp].

[endsect]

[section Synopsis]

   namespace boost{ namespace math{
   
   template<typename T> class ``[link boost_quaternions.quaternions.quat quaternion]``;
   template<>           class ``[link boost_quaternions.quaternions.spec quaternion<float>]``;
   template<>           class ``[link boost_quaternions.quaternion_double quaternion<double>]``; 
   template<>           class ``[link boost_quaternions.quaternion_long_double quaternion<long double>]``; 

   // operators
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_addition_operators operator +]`` (T const & lhs, quaternion<T> const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_addition_operators operator +]`` (quaternion<T> const & lhs, T const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_addition_operators operator +]`` (::std::complex<T> const & lhs, quaternion<T> const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_addition_operators operator +]`` (quaternion<T> const & lhs, ::std::complex<T> const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_addition_operators operator +]`` (quaternion<T> const & lhs, quaternion<T> const & rhs);

   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_subtraction_operators operator -]`` (T const & lhs, quaternion<T> const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_subtraction_operators operator -]`` (quaternion<T> const & lhs, T const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_subtraction_operators operator -]`` (::std::complex<T> const & lhs, quaternion<T> const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_subtraction_operators operator -]`` (quaternion<T> const & lhs, ::std::complex<T> const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_subtraction_operators operator -]`` (quaternion<T> const & lhs, quaternion<T> const & rhs);

   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_multiplication_operators operator *]`` (T const & lhs, quaternion<T> const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_multiplication_operators operator *]`` (quaternion<T> const & lhs, T const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_multiplication_operators operator *]`` (::std::complex<T> const & lhs, quaternion<T> const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_multiplication_operators operator *]`` (quaternion<T> const & lhs, ::std::complex<T> const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_multiplication_operators operator *]`` (quaternion<T> const & lhs, quaternion<T> const & rhs);

   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_division_operators operator /]`` (T const & lhs, quaternion<T> const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_division_operators operator /]`` (quaternion<T> const & lhs, T const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_division_operators operator /]`` (::std::complex<T> const & lhs, quaternion<T> const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_division_operators operator /]`` (quaternion<T> const & lhs, ::std::complex<T> const & rhs);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.binary_division_operators operator /]`` (quaternion<T> const & lhs, quaternion<T> const & rhs); 

   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.unary_plus operator +]`` (quaternion<T> const & q);
   template<typename T> quaternion<T> ``[link boost_quaternions.quaternions.non_mem.unary_minus operator -]`` (quaternion<T> const & q); 

   template<typename T> bool ``[link boost_quaternions.quaternions.non_mem.equality_operators operator ==]`` (T const & lhs, quaternion<T> const & rhs);
   template<typename T> bool ``[link boost_quaternions.quaternions.non_mem.equality_operators operator ==]`` (quaternion<T> const & lhs, T const & rhs);
   template<typename T> bool ``[link boost_quaternions.quaternions.non_mem.equality_operators operator ==]`` (::std::complex<T> const & lhs, quaternion<T> const & rhs);
   template<typename T> bool ``[link boost_quaternions.quaternions.non_mem.equality_operators operator ==]`` (quaternion<T> const & lhs, ::std::complex<T> const & rhs);
   template<typename T> bool ``[link boost_quaternions.quaternions.non_mem.equality_operators operator ==]`` (quaternion<T> const & lhs, quaternion<T> const & rhs);

   template<typename T> bool ``[link boost_quaternions.quaternions.non_mem.inequality_operators operator !=]`` (T const & lhs, quaternion<T> const & rhs);
   template<typename T> bool ``[link boost_quaternions.quaternions.non_mem.inequality_operators operator !=]`` (quaternion<T> const & lhs, T const & rhs);
   template<typename T> bool ``[link boost_quaternions.quaternions.non_mem.inequality_operators operator !=]`` (::std::complex<T> const & lhs, quaternion<T> const & rhs);
   template<typename T> bool ``[link boost_quaternions.quaternions.non_mem.inequality_operators operator !=]`` (quaternion<T> const & lhs, ::std::complex<T> const & rhs);
   template<typename T> bool ``[link boost_quaternions.quaternions.non_mem.inequality_operators operator !=]`` (quaternion<T> const & lhs, quaternion<T> const & rhs); 

   template<typename T, typename charT, class traits>
   ::std::basic_istream<charT,traits>& ``[link boost_quaternions.quaternions.non_mem.stream_extractor operator >>]`` (::std::basic_istream<charT,traits> & is, quaternion<T> & q);

   template<typename T, typename charT, class traits>
   ::std::basic_ostream<charT,traits>& operator ``[link boost_quaternions.quaternions.non_mem.stream_inserter operator <<]`` (::std::basic_ostream<charT,traits> & os, quaternion<T> const & q);

   // values
   template<typename T>	T              ``[link boost_quaternions.quaternions.value_op.real_and_unreal real]``(quaternion<T> const & q);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.value_op.real_and_unreal unreal]``(quaternion<T> const & q);

   template<typename T>	T              ``[link boost_quaternions.quaternions.value_op.sup sup]``(quaternion<T> const & q);
   template<typename T>	T              ``[link boost_quaternions.quaternions.value_op.l1 l1]``(quaternion<T> const & q);
   template<typename T>	T              ``[link boost_quaternions.quaternions.value_op.abs abs]``(quaternion<T> const & q);
   template<typename T>	T              ``[link boost_quaternions.quaternions.value_op.norm norm]``(quaternion<T>const  & q);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.value_op.conj conj]``(quaternion<T> const & q);

   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.creation_spherical spherical]``(T const & rho, T const & theta, T const & phi1, T const & phi2);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.creation_semipolar semipolar]``(T const & rho, T const & alpha, T const & theta1, T const & theta2);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.creation_multipolar multipolar]``(T const & rho1, T const & theta1, T const & rho2, T const & theta2);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.creation_cylindrospherical cylindrospherical]``(T const & t, T const & radius, T const & longitude, T const & latitude);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.creation_cylindrical cylindrical]``(T const & r, T const & angle, T const & h1, T const & h2);

   // transcendentals
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.trans.exp exp]``(quaternion<T> const & q);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.trans.cos cos]``(quaternion<T> const & q);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.trans.sin sin]``(quaternion<T> const & q);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.trans.tan tan]``(quaternion<T> const & q);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.trans.cosh cosh]``(quaternion<T> const & q);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.trans.sinh sinh]``(quaternion<T> const & q);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.trans.tanh tanh]``(quaternion<T> const & q);
   template<typename T>	quaternion<T>  ``[link boost_quaternions.quaternions.trans.pow pow]``(quaternion<T> const & q, int n);

   } // namespace math
   } // namespace boost
   
[endsect]

[section:quat Template Class quaternion]

   namespace boost{ namespace math{
   
   template<typename T>
   class quaternion
   {
   public:

      typedef T ``[link boost_quaternions.quaternions.mem_typedef value_type]``;

      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(T const & requested_a = T(), T const & requested_b = T(), T const & requested_c = T(), T const & requested_d = T());
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(::std::complex<T> const & z0, ::std::complex<T> const & z1 = ::std::complex<T>());
      template<typename X> 
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(quaternion<X> const & a_recopier);

      T                  ``[link boost_quaternions.quaternions.mem_fun.real_and_unreal_parts real]``() const;
      quaternion<T>      ``[link boost_quaternions.quaternions.mem_fun.real_and_unreal_parts unreal]``() const;
      T                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_1]``() const;
      T                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_2]``() const;
      T                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_3]``() const;
      T                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_4]``() const;
      ::std::complex<T>  ``[link boost_quaternions.quaternions.mem_fun.individual_complex__components C_component_1]``() const;
      ::std::complex<T>  ``[link boost_quaternions.quaternions.mem_fun.individual_complex__components C_component_2]``() const;

      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(quaternion<T> const  & a_affecter);
      template<typename X>	
      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(quaternion<X> const  & a_affecter);
      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(T const  & a_affecter);
      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(::std::complex<T> const & a_affecter);

      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.addition_operators operator += ]``(T const & rhs);
      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.addition_operators operator += ]``(::std::complex<T> const & rhs);
      template<typename X>
      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.addition_operators operator += ]``(quaternion<X> const & rhs);

      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.subtraction_operators operator -= ]``(T const & rhs);
      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.subtraction_operators operator -= ]``(::std::complex<T> const & rhs);
      template<typename X>
      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.subtraction_operators operator -= ]``(quaternion<X> const & rhs);

      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.multiplication_operators operator *= ]``(T const & rhs);
      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.multiplication_operators operator *= ]``(::std::complex<T> const & rhs);
      template<typename X>
      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.multiplication_operators operator *= ]``(quaternion<X> const & rhs);

      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.division_operators operator /= ]``(T const & rhs);
      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.division_operators operator /= ]``(::std::complex<T> const & rhs);
      template<typename X>
      quaternion<T>&     ``[link boost_quaternions.quaternions.mem_fun.division_operators operator /= ]``(quaternion<X> const & rhs);
   };

   } // namespace math
   } // namespace boost
   
[endsect]

[section:spec Quaternion Specializations]

   namespace boost{ namespace math{

   template<>
   class quaternion<float>
   {
   public:
      typedef float ``[link boost_quaternions.quaternions.mem_typedef value_type]``;
   	
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(float const & requested_a = 0.0f, float const & requested_b = 0.0f, float const & requested_c = 0.0f, float const & requested_d = 0.0f);
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(::std::complex<float> const & z0, ::std::complex<float> const & z1 = ::std::complex<float>());
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(quaternion<double> const & a_recopier);
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(quaternion<long double> const & a_recopier);
   	
      float                  ``[link boost_quaternions.quaternions.mem_fun.real_and_unreal_parts real]``() const;
      quaternion<float>      ``[link boost_quaternions.quaternions.mem_fun.real_and_unreal_parts unreal]``() const;
      float                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_1]``() const;
      float                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_2]``() const;
      float                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_3]``() const;
      float                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_4]``() const;
      ::std::complex<float>  ``[link boost_quaternions.quaternions.mem_fun.individual_complex__components C_component_1]``() const;
      ::std::complex<float>  ``[link boost_quaternions.quaternions.mem_fun.individual_complex__components C_component_2]``() const;

      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(quaternion<float> const  & a_affecter);
      template<typename X>	
      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(quaternion<X> const  & a_affecter);
      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(float const  & a_affecter);
      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(::std::complex<float> const & a_affecter);

      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.addition_operators operator += ]``(float const & rhs);
      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.addition_operators operator += ]``(::std::complex<float> const & rhs);
      template<typename X>
      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.addition_operators operator += ]``(quaternion<X> const & rhs);

      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.subtraction_operators operator -= ]``(float const & rhs);
      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.subtraction_operators operator -= ]``(::std::complex<float> const & rhs);
      template<typename X>
      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.subtraction_operators operator -= ]``(quaternion<X> const & rhs);

      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.multiplication_operators operator *= ]``(float const & rhs);
      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.multiplication_operators operator *= ]``(::std::complex<float> const & rhs);
      template<typename X>
      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.multiplication_operators operator *= ]``(quaternion<X> const & rhs);

      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.division_operators operator /= ]``(float const & rhs);
      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.division_operators operator /= ]``(::std::complex<float> const & rhs);
      template<typename X>
      quaternion<float>&     ``[link boost_quaternions.quaternions.mem_fun.division_operators operator /= ]``(quaternion<X> const & rhs);
   };
   
[#boost_quaternions.quaternion_double]

   template<>
   class quaternion<double>
   {
   public:
      typedef double ``[link boost_quaternions.quaternions.mem_typedef value_type]``;
   	
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(double const & requested_a = 0.0, double const & requested_b = 0.0, double const & requested_c = 0.0, double const & requested_d = 0.0);
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(::std::complex<double> const & z0, ::std::complex<double> const & z1 = ::std::complex<double>());
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(quaternion<float> const & a_recopier);
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(quaternion<long double> const & a_recopier);
   	
      double                  ``[link boost_quaternions.quaternions.mem_fun.real_and_unreal_parts real]``() const;
      quaternion<double>      ``[link boost_quaternions.quaternions.mem_fun.real_and_unreal_parts unreal]``() const;
      double                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_1]``() const;
      double                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_2]``() const;
      double                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_3]``() const;
      double                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_4]``() const;
      ::std::complex<double>  ``[link boost_quaternions.quaternions.mem_fun.individual_complex__components C_component_1]``() const;
      ::std::complex<double>  ``[link boost_quaternions.quaternions.mem_fun.individual_complex__components C_component_2]``() const;

      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(quaternion<double> const  & a_affecter);
      template<typename X>	
      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(quaternion<X> const  & a_affecter);
      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(double const  & a_affecter);
      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(::std::complex<double> const & a_affecter);

      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.addition_operators operator += ]``(double const & rhs);
      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.addition_operators operator += ]``(::std::complex<double> const & rhs);
      template<typename X>
      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.addition_operators operator += ]``(quaternion<X> const & rhs);

      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.subtraction_operators operator -= ]``(double const & rhs);
      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.subtraction_operators operator -= ]``(::std::complex<double> const & rhs);
      template<typename X>
      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.subtraction_operators operator -= ]``(quaternion<X> const & rhs);

      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.multiplication_operators operator *= ]``(double const & rhs);
      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.multiplication_operators operator *= ]``(::std::complex<double> const & rhs);
      template<typename X>
      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.multiplication_operators operator *= ]``(quaternion<X> const & rhs);

      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.division_operators operator /= ]``(double const & rhs);
      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.division_operators operator /= ]``(::std::complex<double> const & rhs);
      template<typename X>
      quaternion<double>&     ``[link boost_quaternions.quaternions.mem_fun.division_operators operator /= ]``(quaternion<X> const & rhs);
   };

[#boost_quaternions.quaternion_long_double]

   template<>
   class quaternion<long double>
   {
   public:
      typedef long double ``[link boost_quaternions.quaternions.mem_typedef value_type]``;
   	
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(long double const & requested_a = 0.0L, long double const & requested_b = 0.0L, long double const & requested_c = 0.0L, long double const & requested_d = 0.0L);
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(::std::complex<long double> const & z0, ::std::complex<long double> const & z1 = ::std::complex<long double>());
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(quaternion<float> const & a_recopier);
      explicit ``[link boost_quaternions.quaternions.mem_fun.constructors quaternion]``(quaternion<double> const & a_recopier);
   	
      long double                  ``[link boost_quaternions.quaternions.mem_fun.real_and_unreal_parts real]``() const;
      quaternion<long double>      ``[link boost_quaternions.quaternions.mem_fun.real_and_unreal_parts unreal]``() const;
      long double                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_1]``() const;
      long double                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_2]``() const;
      long double                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_3]``() const;
      long double                  ``[link boost_quaternions.quaternions.mem_fun.individual_real_components R_component_4]``() const;
      ::std::complex<long double>  ``[link boost_quaternions.quaternions.mem_fun.individual_complex__components C_component_1]``() const;
      ::std::complex<long double>  ``[link boost_quaternions.quaternions.mem_fun.individual_complex__components C_component_2]``() const;

      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(quaternion<long double> const  & a_affecter);
      template<typename X>	
      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(quaternion<X> const  & a_affecter);
      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(long double const  & a_affecter);
      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.assignment_operators operator = ]``(::std::complex<long double> const & a_affecter);

      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.addition_operators operator += ]``(long double const & rhs);
      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.addition_operators operator += ]``(::std::complex<long double> const & rhs);
      template<typename X>
      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.addition_operators operator += ]``(quaternion<X> const & rhs);

      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.subtraction_operators operator -= ]``(long double const & rhs);
      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.subtraction_operators operator -= ]``(::std::complex<long double> const & rhs);
      template<typename X>
      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.subtraction_operators operator -= ]``(quaternion<X> const & rhs);

      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.multiplication_operators operator *= ]``(long double const & rhs);
      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.multiplication_operators operator *= ]``(::std::complex<long double> const & rhs);
      template<typename X>
      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.multiplication_operators operator *= ]``(quaternion<X> const & rhs);

      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.division_operators operator /= ]``(long double const & rhs);
      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.division_operators operator /= ]``(::std::complex<long double> const & rhs);
      template<typename X>
      quaternion<long double>&     ``[link boost_quaternions.quaternions.mem_fun.division_operators operator /= ]``(quaternion<X> const & rhs);
   };

   } // namespace math
   } // namespace boost
   
[endsect]

[section:mem_typedef Quaternion Member Typedefs]

[*value_type]

Template version:

   typedef T value_type;

Float specialization version:

   typedef float value_type;

Double specialization version:

   typedef double value_type;

Long double specialization version:

   typedef long double value_type;

These provide easy acces to the type the template is built upon.

[endsect]

[section:mem_fun Quaternion Member Functions]
[h3 Constructors]

Template version:

   explicit quaternion(T const & requested_a = T(), T const & requested_b = T(), T const & requested_c = T(), T const & requested_d = T());
   explicit quaternion(::std::complex<T> const & z0, ::std::complex<T> const & z1 = ::std::complex<T>());
   template<typename X>
   explicit quaternion(quaternion<X> const & a_recopier);

Float specialization version:

   explicit quaternion(float const & requested_a = 0.0f, float const & requested_b = 0.0f, float const & requested_c = 0.0f, float const & requested_d = 0.0f);
   explicit quaternion(::std::complex<float> const & z0,::std::complex<float> const & z1 = ::std::complex<float>());
   explicit quaternion(quaternion<double> const & a_recopier); 
   explicit quaternion(quaternion<long double> const & a_recopier);

Double specialization version:

   explicit quaternion(double const & requested_a = 0.0, double const & requested_b = 0.0, double const & requested_c = 0.0, double const & requested_d = 0.0);
   explicit quaternion(::std::complex<double> const & z0, ::std::complex<double> const & z1 = ::std::complex<double>());
   explicit quaternion(quaternion<float> const & a_recopier);
   explicit quaternion(quaternion<long double> const & a_recopier);

Long double specialization version:

   explicit quaternion(long double const & requested_a = 0.0L, long double const & requested_b = 0.0L, long double const & requested_c = 0.0L, long double const & requested_d = 0.0L);
   explicit quaternion(	::std::complex<long double> const & z0, ::std::complex<long double> const & z1 = ::std::complex<long double>());
   explicit quaternion(quaternion<float> const & a_recopier);
   explicit quaternion(quaternion<double> const & a_recopier);

A default constructor is provided for each form, which initializes 
each component to the default values for their type 
(i.e. zero for floating numbers). This constructor can also accept 
one to four base type arguments. A constructor is also provided to 
build quaternions from one or two complex numbers sharing the same 
base type. The unspecialized template also sports a templarized copy 
constructor, while the specialized forms have copy constructors 
from the other two specializations, which are explicit when a risk of 
precision loss exists. For the unspecialized form, the base type's 
constructors must not throw.

Destructors and untemplated copy constructors (from the same type) are 
provided by the compiler. Converting copy constructors make use of a 
templated helper function in a "detail" subnamespace.

[h3 Other member functions]
[h4 Real and Unreal Parts]

   T             real() const;
   quaternion<T> unreal() const;

Like complex number, quaternions do have a meaningful notion of "real part", 
but unlike them there is no meaningful notion of "imaginary part". 
Instead there is an "unreal part" which itself is a quaternion, 
and usually nothing simpler (as opposed to the complex number case). 
These are returned by the first two functions.

[h4 Individual Real Components]

   T R_component_1() const;
   T R_component_2() const;
   T R_component_3() const;
   T R_component_4() const;

A quaternion having four real components, these are returned by these four 
functions. Hence real and R_component_1 return the same value.

[h4 Individual Complex  Components]

   ::std::complex<T>	C_component_1() const;
   ::std::complex<T>	C_component_2() const;

A quaternion likewise has two complex components, and as we have seen above, 
for any quaternion __quat_formula we also have __quat_complex_formula. These functions return them. 
The real part of `q.C_component_1()` is the same as `q.real()`.

[h3 Quaternion Member Operators]
[h4 Assignment Operators]

   quaternion<T>& operator = (quaternion<T> const & a_affecter);
   template<typename X> 
   quaternion<T>& operator = (quaternion<X> const& a_affecter);
   quaternion<T>& operator = (T const& a_affecter);
   quaternion<T>& operator = (::std::complex<T> const& a_affecter);

These perform the expected assignment, with type modification if necessary 
(for instance, assigning from a base type will set the real part to that 
value, and all other components to zero). For the unspecialized form, 
the base type's assignment operators must not throw.

[h4 Addition Operators]

   quaternion<T>& operator += (T const & rhs)
   quaternion<T>& operator += (::std::complex<T> const & rhs);
   template<typename X>	
   quaternion<T>& operator += (quaternion<X> const & rhs);

These perform the mathematical operation `(*this)+rhs` and store the result in 
`*this`. The unspecialized form has exception guards, which the specialized 
forms do not, so as to insure exception safety. For the unspecialized form, 
the base type's assignment operators must not throw.

[h4 Subtraction Operators]

   quaternion<T>& operator -= (T const & rhs)
   quaternion<T>& operator -= (::std::complex<T> const & rhs);
   template<typename X>	
   quaternion<T>& operator -= (quaternion<X> const & rhs);

These perform the mathematical operation `(*this)-rhs` and store the result 
in `*this`. The unspecialized form has exception guards, which the 
specialized forms do not, so as to insure exception safety. 
For the unspecialized form, the base type's assignment operators 
must not throw.

[h4 Multiplication Operators]

   quaternion<T>& operator *= (T const & rhs)
   quaternion<T>& operator *= (::std::complex<T> const & rhs);
   template<typename X>	
   quaternion<T>& operator *= (quaternion<X> const & rhs);

These perform the mathematical operation `(*this)*rhs` [*in this order] 
(order is important as multiplication is not commutative for quaternions) 
and store the result in `*this`. The unspecialized form has exception guards, 
which the specialized forms do not, so as to insure exception safety. 
For the unspecialized form, the base type's assignment operators must not throw.

[h4 Division Operators]

   quaternion<T>& operator /= (T const & rhs)
   quaternion<T>& operator /= (::std::complex<T> const & rhs);
   template<typename X>	
   quaternion<T>& operator /= (quaternion<X> const & rhs);

These perform the mathematical operation `(*this)*inverse_of(rhs)` [*in this 
order] (order is important as multiplication is not commutative for quaternions) 
and store the result in `*this`. The unspecialized form has exception guards, 
which the specialized forms do not, so as to insure exception safety. 
For the unspecialized form, the base type's assignment operators must not throw.

[endsect]
[section:non_mem Quaternion Non-Member Operators]

[h4 Unary Plus]

   template<typename T>	
   quaternion<T> operator + (quaternion<T> const & q);

This unary operator simply returns q.

[h4 Unary Minus]

   template<typename T>
   quaternion<T> operator - (quaternion<T> const & q);

This unary operator returns the opposite of q.

[h4 Binary Addition Operators]

   template<typename T>	quaternion<T>	operator + (T const & lhs, quaternion<T> const & rhs);
   template<typename T>	quaternion<T>	operator + (quaternion<T> const & lhs, T const & rhs);
   template<typename T>	quaternion<T>	operator + (::std::complex<T> const & lhs, quaternion<T> const & rhs);
   template<typename T>	quaternion<T>	operator + (quaternion<T> const & lhs, ::std::complex<T> const & rhs);
   template<typename T>	quaternion<T>	operator + (quaternion<T> const & lhs, quaternion<T> const & rhs);

These operators return `quaternion<T>(lhs) += rhs`.

[h4 Binary Subtraction Operators]

   template<typename T>	quaternion<T>	operator - (T const & lhs, quaternion<T> const & rhs);
   template<typename T>	quaternion<T>	operator - (quaternion<T> const & lhs, T const & rhs);
   template<typename T>	quaternion<T>	operator - (::std::complex<T> const & lhs, quaternion<T> const & rhs);
   template<typename T>	quaternion<T>	operator - (quaternion<T> const & lhs, ::std::complex<T> const & rhs);
   template<typename T>	quaternion<T>	operator - (quaternion<T> const & lhs, quaternion<T> const & rhs);

These operators return `quaternion<T>(lhs) -= rhs`.

[h4 Binary Multiplication Operators]

   template<typename T>	quaternion<T>	operator * (T const & lhs, quaternion<T> const & rhs);
   template<typename T>	quaternion<T>	operator * (quaternion<T> const & lhs, T const & rhs);
   template<typename T>	quaternion<T>	operator * (::std::complex<T> const & lhs, quaternion<T> const & rhs);
   template<typename T>	quaternion<T>	operator * (quaternion<T> const & lhs, ::std::complex<T> const & rhs);
   template<typename T>	quaternion<T>	operator * (quaternion<T> const & lhs, quaternion<T> const & rhs);

These operators return `quaternion<T>(lhs) *= rhs`.

[h4 Binary Division Operators]

   template<typename T>	quaternion<T>	operator / (T const & lhs, quaternion<T> const & rhs);
   template<typename T>	quaternion<T>	operator / (quaternion<T> const & lhs, T const & rhs);
   template<typename T>	quaternion<T>	operator / (::std::complex<T> const & lhs, quaternion<T> const & rhs);
   template<typename T>	quaternion<T>	operator / (quaternion<T> const & lhs, ::std::complex<T> const & rhs);
   template<typename T>	quaternion<T>	operator / (quaternion<T> const & lhs, quaternion<T> const & rhs);

These operators return `quaternion<T>(lhs) /= rhs`. It is of course still an 
error to divide by zero...

[h4 Equality Operators]

   template<typename T>	bool	operator == (T const & lhs, quaternion<T> const & rhs);
   template<typename T>	bool	operator == (quaternion<T> const & lhs, T const & rhs);
   template<typename T>	bool	operator == (::std::complex<T> const & lhs, quaternion<T> const & rhs);
   template<typename T>	bool	operator == (quaternion<T> const & lhs, ::std::complex<T> const & rhs);
   template<typename T>	bool	operator == (quaternion<T> const & lhs, quaternion<T> const & rhs);

These return true if and only if the four components of `quaternion<T>(lhs)`
are equal to their counterparts in `quaternion<T>(rhs)`. As with any 
floating-type entity, this is essentially meaningless.

[h4 Inequality Operators]

   template<typename T>	bool	operator != (T const & lhs, quaternion<T> const & rhs);
   template<typename T>	bool	operator != (quaternion<T> const & lhs, T const & rhs);
   template<typename T>	bool	operator != (::std::complex<T> const & lhs, quaternion<T> const & rhs);
   template<typename T>	bool	operator != (quaternion<T> const & lhs, ::std::complex<T> const & rhs);
   template<typename T>	bool	operator != (quaternion<T> const & lhs, quaternion<T> const & rhs);

These return true if and only if `quaternion<T>(lhs) == quaternion<T>(rhs)` is 
false. As with any floating-type entity, this is essentially meaningless.

[h4 Stream Extractor]

   template<typename T, typename charT, class traits>
   ::std::basic_istream<charT,traits>& operator >> (::std::basic_istream<charT,traits> & is, quaternion<T> & q);

Extracts a quaternion q of one of the following forms 
(with a, b, c and d of type `T`):

[^a (a), (a,b), (a,b,c), (a,b,c,d) (a,(c)), (a,(c,d)), ((a)), ((a),c), ((a),(c)), ((a),(c,d)), ((a,b)), ((a,b),c), ((a,b),(c)), ((a,b),(c,d))]

The input values must be convertible to `T`. If bad input is encountered, 
calls `is.setstate(ios::failbit)` (which may throw ios::failure (27.4.5.3)).

[*Returns:] `is`.

The rationale for the list of accepted formats is that either we have a 
list of up to four reals, or else we have a couple of complex numbers, 
and in that case if it formated as a proper complex number, then it should 
be accepted. Thus potential ambiguities are lifted (for instance (a,b) is 
(a,b,0,0) and not (a,0,b,0), i.e. it is parsed as a list of two real numbers 
and not two complex numbers which happen to have imaginary parts equal to zero).

[h4 Stream Inserter]

   template<typename T, typename charT, class traits>
   ::std::basic_ostream<charT,traits>& operator << (::std::basic_ostream<charT,traits> & os, quaternion<T> const & q);

Inserts the quaternion q onto the stream `os` as if it were implemented as follows:

   template<typename T, typename charT, class traits>
   ::std::basic_ostream<charT,traits>& operator << (	
                  ::std::basic_ostream<charT,traits> & os,
                  quaternion<T> const & q)
   {
      ::std::basic_ostringstream<charT,traits>	s;

      s.flags(os.flags());
      s.imbue(os.getloc());
      s.precision(os.precision());

      s << '(' << q.R_component_1() << ','
               << q.R_component_2() << ','
               << q.R_component_3() << ','
               << q.R_component_4() << ')';

      return os << s.str();
   }
   
[endsect]

[section:value_op Quaternion Value Operations]

[h4 real and unreal]

   template<typename T>	T              real(quaternion<T> const & q);
   template<typename T>	quaternion<T>  unreal(quaternion<T> const & q);

These return `q.real()` and `q.unreal()` respectively.

[h4 conj]

   template<typename T>	quaternion<T>  conj(quaternion<T> const & q);

This returns the conjugate of the quaternion.

[h4 sup]

template<typename T>	T  sup(quaternion<T> const & q);

This return the sup norm (the greatest among 
`abs(q.R_component_1())...abs(q.R_component_4()))` of the quaternion.

[h4 l1]

   template<typename T>	T  l1(quaternion<T> const & q);

This return the l1 norm `(abs(q.R_component_1())+...+abs(q.R_component_4()))`
of the quaternion.

[h4 abs]

   template<typename T>	T  abs(quaternion<T> const & q);

This return the magnitude (Euclidian norm) of the quaternion.

[h4 norm]

   template<typename T>	T  norm(quaternion<T>const  & q);

This return the (Cayley) norm of the quaternion. 
The term "norm" might be confusing, as most people associate it with the 
Euclidian norm (and quadratic functionals). For this version of 
(the mathematical objects known as) quaternions, the Euclidian norm 
(also known as magnitude) is the square root of the Cayley norm.

[endsect]

[section:create Quaternion Creation Functions]

   template<typename T>	quaternion<T>	spherical(T const & rho, T const & theta, T const & phi1, T const & phi2);
   template<typename T>	quaternion<T>	semipolar(T const & rho, T const & alpha, T const & theta1, T const & theta2);
   template<typename T>	quaternion<T>	multipolar(T const & rho1, T const & theta1, T const & rho2, T const & theta2);
   template<typename T>	quaternion<T>	cylindrospherical(T const & t, T const & radius, T const & longitude, T const & latitude);
   template<typename T>	quaternion<T>	cylindrical(T const & r, T const & angle, T const & h1, T const & h2);

These build quaternions in a way similar to the way polar builds complex 
numbers, as there is no strict equivalent to polar coordinates for quaternions.

[#boost_quaternions.quaternions.creation_spherical] `spherical` is a simple transposition of `polar`, it takes as inputs 
a (positive) magnitude and a point on the hypersphere, given by three angles. 
The first of these, `theta` has a natural range of `-pi` to `+pi`, and the other 
two have natural ranges of `-pi/2` to `+pi/2` (as is the case with the usual 
spherical coordinates in __R3). Due to the many symmetries and periodicities, 
nothing untoward happens if the magnitude is negative or the angles are 
outside their natural ranges. The expected degeneracies (a magnitude of 
zero ignores the angles settings...) do happen however.

[#boost_quaternions.quaternions.creation_cylindrical] `cylindrical` is likewise a simple transposition of the usual 
cylindrical coordinates in __R3, which in turn is another derivative of 
planar polar coordinates. The first two inputs are the polar coordinates of 
the first __C component of the quaternion. The third and fourth inputs 
are placed into the third and fourth __R components of the quaternion, 
respectively.

[#boost_quaternions.quaternions.creation_multipolar] `multipolar` is yet another simple generalization of polar coordinates. 
This time, both __C components of the quaternion are given in polar coordinates.

[#boost_quaternions.quaternions.creation_cylindrospherical] `cylindrospherical` is specific to quaternions. It is often interesting to 
consider __H as the cartesian product of __R by __R3 (the quaternionic 
multiplication as then a special form, as given here). This function 
therefore builds a quaternion from this representation, with the __R3 
component given in usual __R3 spherical coordinates.

[#boost_quaternions.quaternions.creation_semipolar] `semipolar` is another generator which is specific to quaternions. 
It takes as a first input the magnitude of the quaternion, as a 
second input an angle in the range `0` to `+pi/2` such that magnitudes 
of the first two __C components of the quaternion are the product of the 
first input and the sine and cosine of this angle, respectively, and finally 
as third and fourth inputs angles in the range `-pi/2` to `+pi/2` which 
represent the arguments of the first and second __C components of 
the quaternion, respectively. As usual, nothing untoward happens if 
what should be magnitudes are negative numbers or angles are out of their 
natural ranges, as symmetries and periodicities kick in.

In this version of our implementation of quaternions, there is no 
analogue of the complex value operation `arg` as the situation is 
somewhat more complicated. Unit quaternions are linked both to 
rotations in __R3 and in __R4, and the correspondences are not too complicated, 
but there is currently a lack of standard (de facto or de jure) matrix 
library with which the conversions could work. This should be remedied in 
a further revision. In the mean time, an example of how this could be 
done is presented here for 
[@../../../quaternion/HSO3.hpp __R3], and here for 
[@../../../quaternion/HSO4.hpp __R4] 
([@../../../quaternion/HSO3SO4.cpp example test file]).

[endsect]

[section:trans Quaternion Transcendentals]

There is no `log` or `sqrt` provided for quaternions in this implementation, 
and `pow` is likewise restricted to integral powers of the exponent. 
There are several reasons to this: on the one hand, the equivalent of 
analytic continuation for quaternions ("branch cuts") remains to be 
investigated thoroughly (by me, at any rate...), and we wish to avoid the 
nonsense introduced in the standard by exponentiations of complexes by 
complexes (which is well defined, but not in the standard...). 
Talking of nonsense, saying that `pow(0,0)` is "implementation defined" is just 
plain brain-dead...

We do, however provide several transcendentals, chief among which is the 
exponential. This author claims the complete proof of the "closed formula" 
as his own, as well as its independant invention (there are claims to prior 
invention of the formula, such as one by Professor Shoemake, and it is 
possible that the formula had been known a couple of centuries back, but in 
absence of bibliographical reference, the matter is pending, awaiting further 
investigation; on the other hand, the definition and existence of the 
exponential on the quaternions, is of course a fact known for a very long time). 
Basically, any converging power series with real coefficients which allows for a 
closed formula in __C can be transposed to __H. More transcendentals of this 
type could be added in a further revision upon request. It should be 
noted that it is these functions which force the dependency upon the 
[@../../../../../boost/math/special_functions/sinc.hpp boost/math/special_functions/sinc.hpp] and the 
[@../../../../../boost/math/special_functions/sinhc.hpp boost/math/special_functions/sinhc.hpp] headers.

[h4 exp]

   template<typename T>	quaternion<T> exp(quaternion<T> const & q);

Computes the exponential of the quaternion.

[h4 cos]

   template<typename T>	quaternion<T>  cos(quaternion<T> const & q);

Computes the cosine of the quaternion

[h4 sin]

   template<typename T>	quaternion<T>  sin(quaternion<T> const & q);

Computes the sine of the quaternion.

[h4 tan]

   template<typename T>	quaternion<T>  tan(quaternion<T> const & q);

Computes the tangent of the quaternion.

[h4 cosh]

   template<typename T>	quaternion<T>  cosh(quaternion<T> const & q);

Computes the hyperbolic cosine of the quaternion.

[h4 sinh]

   template<typename T>	quaternion<T>  sinh(quaternion<T> const & q);

Computes the hyperbolic sine of the quaternion.

[h4 tanh]

   template<typename T>	quaternion<T>  tanh(quaternion<T> const & q);

Computes the hyperbolic tangent of the quaternion.

[h4 pow]

   template<typename T>	quaternion<T>  pow(quaternion<T> const & q, int n);

Computes the n-th power of the quaternion q.

[endsect]

[section Test Program]

The [@../../../quaternion/quaternion_test.cpp quaternion_test.cpp] 
test program tests quaternions specializations for float, double and long double 
([@../../../quaternion/output.txt sample output], with message output 
enabled).

If you define the symbol boost_quaternions_TEST_VERBOSE, you will get 
additional output ([@../../../quaternion/output_more.txt verbose output]); 
this will only be helpfull if you enable message output at the same time, 
of course (by uncommenting the relevant line in the test or by adding 
[^--log_level=messages] to your command line,...). In that case, and if you 
are running interactively, you may in addition define the symbol 
BOOST_INTERACTIVE_TEST_INPUT_ITERATOR to interactively test the input 
operator with input of your choice from the standard input 
(instead of hard-coding it in the test).

[endsect]

[section:exp The Quaternionic Exponential]

Please refer to the following PDF's:

*[@../../../quaternion/TQE.pdf The Quaternionic Exponential (and beyond)]
*[@../../../quaternion/TQE_EA.pdf The Quaternionic Exponential (and beyond) ERRATA & ADDENDA]

[endsect]

[section Acknowledgements]

The mathematical text has been typeset with 
[@http://www.nisus-soft.com/ Nisus Writer]. Jens Maurer has helped with 
portability and standard adherence, and was the Review Manager 
for this library. More acknowledgements in the History section. 
Thank you to all who contributed to the discution about this library.

[endsect]

[section History]

* 1.5.8 - 17/12/2005: Converted documentation to Quickbook Format.
* 1.5.7 - 24/02/2003: transitionned to the unit test framework; <boost/config.hpp> now included by the library header (rather than the test files).
* 1.5.6 - 15/10/2002: Gcc2.95.x and stlport on linux compatibility by Alkis Evlogimenos (alkis@routescience.com).
* 1.5.5 - 27/09/2002: Microsoft VCPP 7 compatibility, by Michael Stevens (michael@acfr.usyd.edu.au); requires the /Za compiler option.
* 1.5.4 - 19/09/2002: fixed problem with multiple inclusion (in different translation units); attempt at an improved compatibility with Microsoft compilers, by Michael Stevens (michael@acfr.usyd.edu.au) and Fredrik Blomqvist; other compatibility fixes.
* 1.5.3 - 01/02/2002: bugfix and Gcc 2.95.3 compatibility by Douglas Gregor (gregod@cs.rpi.edu).
* 1.5.2 - 07/07/2001: introduced namespace math.
* 1.5.1 - 07/06/2001: (end of Boost review) now includes <boost/math/special_functions/sinc.hpp> and <boost/math/special_functions/sinhc.hpp> instead of <boost/special_functions.hpp>; corrected bug in sin (Daryle Walker); removed check for self-assignment (Gary Powel); made converting functions explicit (Gary Powel); added overflow guards for division operators and abs (Peter Schmitteckert); added sup and l1; used Vesa Karvonen's CPP metaprograming technique to simplify code.
* 1.5.0 - 26/03/2001: boostification, inlining of all operators except input, output and pow, fixed exception safety of some members (template version) and output operator, added spherical, semipolar, multipolar, cylindrospherical and cylindrical.
* 1.4.0 - 09/01/2001: added tan and tanh.
* 1.3.1 - 08/01/2001: cosmetic fixes.
* 1.3.0 - 12/07/2000: pow now uses Maarten Hilferink's (mhilferink@tip.nl) algorithm.
* 1.2.0 - 25/05/2000: fixed the division operators and output; changed many signatures.
* 1.1.0 - 23/05/2000: changed sinc into sinc_pi; added sin, cos, sinh, cosh.
* 1.0.0 - 10/08/1999: first public version. 

[endsect]
[section To Do]

* Improve testing.
* Rewrite input operatore using Spirit (creates a dependency).
* Put in place an Expression Template mechanism (perhaps borrowing from uBlas).
* Use uBlas for the link with rotations (and move from the 
[@../../../quaternion/HSO3SO4.cpp example] 
implementation to an efficient one). 
    
[endsect]
[endsect]
