// SPDX-License-Identifier: Apache-2.0
// 
// Copyright 2008-2016 Conrad Sanderson (https://conradsanderson.id.au)
// Copyright 2008-2016 National ICT Australia (NICTA)
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// https://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ------------------------------------------------------------------------


//! \addtogroup gmm_misc
//! @{


namespace gmm_priv
{


template<typename eT>
inline
running_mean_scalar<eT>::running_mean_scalar()
  : counter(uword(0))
  , r_mean (   eT(0))
  {
  arma_debug_sigprint_this(this);
  }



template<typename eT>
inline
running_mean_scalar<eT>::running_mean_scalar(const running_mean_scalar<eT>& in)
  : counter(in.counter)
  , r_mean (in.r_mean )
  {
  arma_debug_sigprint_this(this);
  }



template<typename eT>
inline
const running_mean_scalar<eT>&
running_mean_scalar<eT>::operator=(const running_mean_scalar<eT>& in)
  {
  arma_debug_sigprint();
  
  counter = in.counter;
  r_mean  = in.r_mean;
  
  return *this;
  }



template<typename eT>
inline
void
running_mean_scalar<eT>::operator() (const eT X)
  {
  arma_debug_sigprint();
  
  counter++;
  
  if(counter > 1)
    {
    const eT old_r_mean = r_mean;
    
    r_mean = old_r_mean + (X - old_r_mean)/counter;
    }
  else
    {
    r_mean = X;
    }
  }



template<typename eT>
inline
void
running_mean_scalar<eT>::reset()
  {
  arma_debug_sigprint();
  
  counter = 0;
  r_mean  = eT(0);
  }



template<typename eT>
inline
uword
running_mean_scalar<eT>::count() const
  {
  return counter;
  }



template<typename eT>
inline
eT
running_mean_scalar<eT>::mean() const
  {
  return r_mean;
  }



//
//
//



template<typename eT>
arma_inline
eT
distance<eT, uword(1)>::eval(const uword N, const eT* A, const eT* B, const eT*)
  {
  eT acc1 = eT(0);
  eT acc2 = eT(0);
  
  uword i,j;
  for(i=0, j=1; j<N; i+=2, j+=2)
    {
    eT tmp_i = A[i];
    eT tmp_j = A[j];
    
    tmp_i -= B[i];
    tmp_j -= B[j];
    
    acc1 += tmp_i*tmp_i;
    acc2 += tmp_j*tmp_j;
    }
  
  if(i < N)
    {
    const eT tmp_i = A[i] - B[i];
    
    acc1 += tmp_i*tmp_i;
    }
  
  return (acc1 + acc2);
  }



template<typename eT>
arma_inline
eT
distance<eT, uword(2)>::eval(const uword N, const eT* A, const eT* B, const eT* C)
  {
  eT acc1 = eT(0);
  eT acc2 = eT(0);
  
  uword i,j;
  for(i=0, j=1; j<N; i+=2, j+=2)
    {
    eT tmp_i = A[i];
    eT tmp_j = A[j];
    
    tmp_i -= B[i];
    tmp_j -= B[j];
    
    acc1 += (tmp_i*tmp_i) * C[i];
    acc2 += (tmp_j*tmp_j) * C[j];
    }
  
  if(i < N)
    {
    const eT tmp_i = A[i] - B[i];
    
    acc1 += (tmp_i*tmp_i) * C[i];
    }
  
  return (acc1 + acc2);
  }

}


//! @}