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## Struct template weighted_covariance_impl

boost::accumulators::impl::weighted_covariance_impl — Weighted Covariance Estimator.

## Synopsis

    // In header: <boost/accumulators/statistics/weighted_covariance.hpp>

    template<typename Sample, typename Weight, typename VariateType,
             typename VariateTag>
    struct weighted_covariance_impl {
      // types
      typedef numeric::functional::multiplies< Weight, typename numeric::functional::average< Sample, std::size_t >::result_type >::result_type      weighted_sample_type;
      typedef numeric::functional::multiplies< Weight, typename numeric::functional::average< VariateType, std::size_t >::result_type >::result_type weighted_variate_type;
      typedef numeric::functional::outer_product< weighted_sample_type, weighted_variate_type >::result_type                                         result_type;

      // construct/copy/destruct
      template<typename Args> weighted_covariance_impl(Args const &);

      // public member functions
      template<typename Args> void operator()(Args const &);
      result_type result(dont_care) const;
    };

## Description

An iterative Monte Carlo estimator for the weighted covariance , where is a sample and a variate, is given by:

Equation 1.27.

and being the weighted means of the samples and variates and the sum of the first weights .

### `weighted_covariance_impl` public construct/copy/destruct

1.     template<typename Args> weighted_covariance_impl(Args const & args);

### `weighted_covariance_impl` public member functions

1.     template<typename Args> void operator()(Args const & args);

2.     result_type result(dont_care) const;