Struct template lazy_weighted_variance_impl

Boost C++ Libraries

Struct template lazy_weighted_variance_impl

boost::accumulators::impl::lazy_weighted_variance_impl — Lazy calculation of variance of weighted samples.

Synopsis

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

template<typename Sample, typename Weight, typename MeanFeature> 
struct lazy_weighted_variance_impl : public accumulator_base {
  // types
  typedef numeric::functional::multiplies< Sample, Weight >::result_type    weighted_sample;
  typedef numeric::functional::fdiv< weighted_sample, Weight >::result_type result_type;    

  // construct/copy/destruct
  lazy_weighted_variance_impl(dont_care);

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

Description

The default implementation of the variance of weighted samples is based on the second moment (weighted_moment<2>) and the mean (weighted_mean):

Equation 1.48.

where is the number of samples.

`lazy_weighted_variance_impl` public construct/copy/destruct

```
lazy_weighted_variance_impl(dont_care);
```

`lazy_weighted_variance_impl` public member functions

template<typename Args> result_type result(Args const & args) const;