// Extension: check for an empty gslice.
  bool _M_empty() const { return _M_lengths.size() == 0; }

  // Extension: number of indices this gslice represents.  (For a degenerate
  // gslice, they're not necessarily all distinct.)
  size_t _M_size() const {
    return !this->_M_empty()
      ? accumulate(_M_lengths._M_first + 1,
                   _M_lengths._M_first + _M_lengths._M_size,
                   _M_lengths[0],
                   multiplies<size_t>())
      : 0;
  }

private:
  size_t _M_start;
  valarray<size_t> _M_lengths;
  valarray<size_t> _M_strides;
};

// This is not an STL iterator.  It is constructed from a gslice, and it
// steps through the gslice indices in sequence.  See 23.3.6 of the C++
// standard, paragraphs 2-3, for an explanation of the sequence.  At
// each step we get two things: the ordinal (i.e. number of steps taken),
// and the one-dimensional index.

template <class _Size>
struct _Gslice_Iter_tmpl {
  _Gslice_Iter_tmpl(const gslice& __gslice)
    : _M_step(0), _M_1d_idx(__gslice.start()),
      _M_indices(size_t(0), __gslice._M_lengths.size()),
      _M_gslice(__gslice)
    {}
    
  bool _M_done() const { return _M_indices[0] == _M_gslice._M_lengths[0]; }

  bool _M_incr();

  _Size _M_step;
  _Size _M_1d_idx;

  valarray<_Size> _M_indices;
  const gslice& _M_gslice;
};

typedef _Gslice_Iter_tmpl<size_t> _Gslice_Iter;

template <class _Tp>
class gslice_array {
  friend class valarray<_Tp>;
public:
  typedef _Tp value_type;

  void operator= (const valarray<value_type>& __x) const {
    if (!_M_gslice._M_empty()) {
      _Gslice_Iter __i(_M_gslice);
      do _M_array[__i._M_1d_idx] = __x[__i._M_step]; while(__i._M_incr());
    }
  }

  void operator*= (const valarray<value_type>& __x) const {
    if (!_M_gslice._M_empty()) {
      _Gslice_Iter __i(_M_gslice);
      do _M_array[__i._M_1d_idx] *= __x[__i._M_step]; while(__i._M_incr());
    }
  }

  void operator/= (const valarray<value_type>& __x) const {
    if (!_M_gslice._M_empty()) {
      _Gslice_Iter __i(_M_gslice);
      do _M_array[__i._M_1d_idx] /= __x[__i._M_step]; while(__i._M_incr());
    }
  }

  void operator%= (const valarray<value_type>& __x) const {
    if (!_M_gslice._M_empty()) {
      _Gslice_Iter __i(_M_gslice);
      do _M_array[__i._M_1d_idx] %= __x[__i._M_step]; while(__i._M_incr());
    }
  }

  void operator+= (const valarray<value_type>& __x) const {
    if (!_M_gslice._M_empty()) {
      _Gslice_Iter __i(_M_gslice);
      do _M_array[__i._M_1d_idx] += __x[__i._M_step]; while(__i._M_incr());
    }
  }

  void operator-= (const valarray<value_type>& __x) const {
    if (!_M_gslice._M_empty()) {
      _Gslice_Iter __i(_M_gslice);
      do _M_array[__i._M_1d_idx] -= __x[__i._M_step]; while(__i._M_incr());
    }
  }

  void operator^= (const valarray<value_type>& __x) const {
    if (!_M_gslice._M_empty()) {
      _Gslice_Iter __i(_M_gslice);
      do _M_array[__i._M_1d_idx] ^= __x[__i._M_step]; while(__i._M_incr());
    }
  }

  void operator&= (const valarray<value_type>& __x) const {
    if (!_M_gslice._M_empty()) {
      _Gslice_Iter __i(_M_gslice);
      do _M_array[__i._M_1d_idx] &= __x[__i._M_step]; while(__i._M_incr());
    }
  }

  void operator|= (const valarray<value_type>& __x) const {
    if (!_M_gslice._M_empty()) {
      _Gslice_Iter __i(_M_gslice);
      do _M_array[__i._M_1d_idx] |= __x[__i._M_step]; while(__i._M_incr());
    }
  }

  void operator<<= (const valarray<value_type>& __x) const {
    if (!_M_gslice._M_empty()) {
      _Gslice_Iter __i(_M_gslice);
      do _M_array[__i._M_1d_idx] <<= __x[__i._M_step]; while(__i._M_incr());
    }
  }

  void operator>>= (const valarray<value_type>& __x) const {
    if (!_M_gslice._M_empty()) {
      _Gslice_Iter __i(_M_gslice);
      do _M_array[__i._M_1d_idx] >>= __x[__i._M_step]; while(__i._M_incr());
    }
  }

  void operator= (const value_type& __c) const {
    if (!_M_gslice._M_empty()) {
      _Gslice_Iter __i(_M_gslice);
      do _M_array[__i._M_1d_idx] = __c; while(__i._M_incr());
    }
  }

  ~gslice_array() {}

private:                        
  gslice_array(gslice __gslice, valarray<_Tp>& __array)
    : _M_gslice(__gslice), _M_array(__array)
    {}

  gslice                _M_gslice;
  valarray<value_type>& _M_array;

private:                        // Disable assignment
  void operator=(const gslice_array&);
};

// valarray member functions dealing with gslice and gslice_array.  Note
// that it is illegal (behavior is undefined) to construct a gslice_array
// from a degenerate gslice.

template <class _Tp>
inline valarray<_Tp>::valarray(const gslice_array<_Tp>& __x)
  : _Valarray_base<_Tp>(__x._M_gslice._M_size())
{
  typedef typename __type_traits<_Tp>::has_trivial_default_constructor
          _Is_Trivial;
  _M_initialize(_Is_Trivial());  
  *this = __x;
}

template <class _Tp>
inline gslice_array<_Tp> valarray<_Tp>::operator[](gslice __slice) {
  return gslice_array<_Tp>(__slice, *this);
}


//----------------------------------------------------------------------
// mask_array

template <class _Tp>
class mask_array {
  friend class valarray<_Tp>;
public:
  typedef _Tp value_type;

  void operator=(const valarray<value_type>& __x) const {
    size_t __idx = 0;
    for (size_t __i = 0; __i < _M_array.size(); ++__i)
      if (_M_mask[__i]) _M_array[__i] = __x[__idx++];
  }

  void operator*=(const valarray<value_type>& __x) const {
    size_t __idx = 0;
    for (size_t __i = 0; __i < _M_array.size(); ++__i)
      if (_M_mask[__i]) _M_array[__i] *= __x[__idx++];
  }

  void operator/=(const valarray<value_type>& __x) const {
    size_t __idx = 0;
    for (size_t __i = 0; __i < _M_array.size(); ++__i)
      if (_M_mask[__i]) _M_array[__i] /= __x[__idx++];
  }

  void operator%=(const valarray<value_type>& __x) const {
    size_t __idx = 0;
    for (size_t __i = 0; __i < _M_array.size(); ++__i)
      if (_M_mask[__i]) _M_array[__i] %= __x[__idx++];
  }

  void operator+=(const valarray<value_type>& __x) const {
    size_t __idx = 0;
    for (size_t __i = 0; __i < _M_array.size(); ++__i)
      if (_M_mask[__i]) _M_array[__i] += __x[__idx++];
  }

  void operator-=(const valarray<value_type>& __x) const {
    size_t __idx = 0;
    for (size_t __i = 0; __i < _M_array.size(); ++__i)
      if (_M_mask[__i]) _M_array[__i] -= __x[__idx++];
  }
  
  void operator^=(const valarray<value_type>& __x) const {
    size_t __idx = 0;
    for (size_t __i = 0; __i < _M_array.size(); ++__i)
      if (_M_mask[__i]) _M_array[__i] ^= __x[__idx++];
  }

  void operator&=(const valarray<value_type>& __x) const {
    size_t __idx = 0;
    for (size_t __i = 0; __i < _M_array.size(); ++__i)
      if (_M_mask[__i]) _M_array[__i] &= __x[__idx++];
  }

  void operator|=(const valarray<value_type>& __x) const {
    size_t __idx = 0;
    for (size_t __i = 0; __i < _M_array.size(); ++__i)
      if (_M_mask[__i]) _M_array[__i] |= __x[__idx++];
  }

  void operator<<=(const valarray<value_type>& __x) const {
    size_t __idx = 0;
    for (size_t __i = 0; __i < _M_array.size(); ++__i)
      if (_M_mask[__i]) _M_array[__i] <<= __x[__idx++];
  }

  void operator>>=(const valarray<value_type>& __x) const {
    size_t __idx = 0;
    for (size_t __i = 0; __i < _M_array.size(); ++__i)
      if (_M_mask[__i]) _M_array[__i] >>= __x[__idx++];
  }

  void operator=(const value_type& __c) const {
    for (size_t __i = 0; __i < _M_array.size(); ++__i)
      if (_M_mask[__i]) _M_array[__i] = __c;
  }

  ~mask_array() {}

  // Extension: number of true values in the mask
  size_t _M_num_true() const {
    size_t __result = 0;
    for (size_t __i = 0; __i < _M_mask.size(); ++__i)
      if (_M_mask[__i]) ++__result;
    return __result;
  }

private:
  mask_array(const valarray<bool>& __mask, valarray<_Tp>& __array)
    : _M_mask(__mask), _M_array(__array)
    {}

  valarray<bool> _M_mask;
  valarray<_Tp>& _M_array;

private:                        // Disable assignment
  void operator=(const mask_array&);
};

// valarray member functions dealing with mask_array

template <class _Tp>
inline valarray<_Tp>::valarray(const mask_array<_Tp>& __x)
  : _Valarray_base<_Tp>(__x._M_num_true())
{
  typedef typename __type_traits<_Tp>::has_trivial_default_constructor
          _Is_Trivial;
  _M_initialize(_Is_Trivial());  
  *this = __x;
}

// Behavior is undefined if __x._M_num_true() != this->size()
template <class _Tp>
inline valarray<_Tp>& valarray<_Tp>::operator=(const mask_array<_Tp>& __x) {
  size_t __idx = 0;
  for (size_t __i = 0; __i < __x._M_array.size(); ++__i)
    if (__x._M_mask[__i]) (*this)[__idx++] = __x._M_array[__i];
  return *this;
}

template <class _Tp>
inline mask_array<_Tp> valarray<_Tp>::operator[](const valarray<bool>& __mask)
{
  return mask_array<_Tp>(__mask, *this);
}


//----------------------------------------------------------------------
// indirect_array

template <class _Tp>
class indirect_array {
  friend class valarray<_Tp>;
public:
  typedef _Tp value_type;

  void operator=(const valarray<value_type>& __x) const {
    for (size_t __i = 0; __i < _M_addr.size(); ++__i)
      _M_array[_M_addr[__i]] = __x[__i];
  }

  void operator*=(const valarray<value_type>& __x) const {
    for (size_t __i = 0; __i < _M_addr.size(); ++__i)
      _M_array[_M_addr[__i]] *= __x[__i];
  }

  void operator/=(const valarray<value_type>& __x) const {
    for (size_t __i = 0; __i < _M_addr.size(); ++__i)
      _M_array[_M_addr[__i]] /= __x[__i];
  }

  void operator%=(const valarray<value_type>& __x) const {
    for (size_t __i = 0; __i < _M_addr.size(); ++__i)
      _M_array[_M_addr[__i]] %= __x[__i];
  }

  void operator+=(const valarray<value_type>& __x) const {
    for (size_t __i = 0; __i < _M_addr.size(); ++__i)
      _M_array[_M_addr[__i]] += __x[__i];
  }

  void operator-=(const valarray<value_type>& __x) const {
    for (size_t __i = 0; __i < _M_addr.size(); ++__i)
      _M_array[_M_addr[__i]] -= __x[__i];
  }

  void operator^=(const valarray<value_type>& __x) const {
    for (size_t __i = 0; __i < _M_addr.size(); ++__i)
      _M_array[_M_addr[__i]] ^= __x[__i];
  }

  void operator&=(const valarray<value_type>& __x) const {
    for (size_t __i = 0; __i < _M_addr.size(); ++__i)
      _M_array[_M_addr[__i]] &= __x[__i];
  }

  void operator|=(const valarray<value_type>& __x) const {
    for (size_t __i = 0; __i < _M_addr.size(); ++__i)
      _M_array[_M_addr[__i]] |= __x[__i];
  }

  void operator<<=(const valarray<value_type>& __x) const {
    for (size_t __i = 0; __i < _M_addr.size(); ++__i)
      _M_array[_M_addr[__i]] <<= __x[__i];
  }

  void operator>>=(const valarray<value_type>& __x) const {
    for (size_t __i = 0; __i < _M_addr.size(); ++__i)
      _M_array[_M_addr[__i]] >>= __x[__i];
  }

  void operator=(const value_type& __c) const {
    for (size_t __i = 0; __i < _M_addr.size(); ++__i)
      _M_array[_M_addr[__i]] = __c;
  }

  ~indirect_array() {}

private:
  indirect_array(const valarray<size_t>& __addr, valarray<_Tp>& __array)
    : _M_addr(__addr), _M_array(__array)
    {}

  valarray<size_t> _M_addr;
  valarray<_Tp>&   _M_array;

private:                        // Disable assignment
  void operator=(const indirect_array&);
};

// valarray member functions dealing with indirect_array

template <class _Tp>
inline valarray<_Tp>::valarray(const indirect_array<_Tp>& __x)
  : _Valarray_base<_Tp>(__x._M_addr.size())
{
  typedef typename __type_traits<_Tp>::has_trivial_default_constructor
          _Is_Trivial;
  _M_initialize(_Is_Trivial());  
  *this = __x;
}


template <class _Tp>
inline indirect_array<_Tp>
valarray<_Tp>::operator[](const valarray<size_t>& __addr)
{
  return indirect_array<_Tp>(__addr, *this);
}

__STL_END_NAMESPACE

#  undef __STL_DO_ABS
#  undef __STL_DO_ACOS
#  undef __STL_DO_ASIN
#  undef __STL_DO_ATAN
#  undef __STL_DO_ATAN2
#  undef __STL_DO_COS
#  undef __STL_DO_COSH
#  undef __STL_DO_LOG
#  undef __STL_DO_LOG10
#  undef __STL_DO_POW
#  undef __STL_DO_SIN
#  undef __STL_DO_SINH
#  undef __STL_DO_SQRT
#  undef __STL_DO_TAN
#  undef __STL_DO_TANH

# if !defined (__STL_LINK_TIME_INSTANTIATION)
#  include <stl_valarray.c>
# endif

#endif /* __SGI_STL_VALARRAY */


// Local Variables:
// mode:C++
// End: