marley::ResponseTable Class Reference

A table of nuclear responses for computing inclusive cross sections. More...

#include <ResponseTable.hh>

Public Member Functions
	ResponseTable (std::shared_ptr< std::vector< double > > &wvec, std::shared_ptr< std::vector< double > > &qvec, std::shared_ptr< std::vector< NuclearResponses > > &resp)
const std::vector< NuclearResponses > &	get_responses () const
	Access the nuclear responses.
NuclearResponses	interpolate (double w, double q) const
const std::vector< double > &	q_grid () const
	Access the 3-momentum transfer grid points.
double	q_max () const
	Retrieve the maximum q value.
double	q_min () const
	Retrieve the minimum q value.
size_t	response_index (size_t iw, size_t iq) const
const std::vector< double > &	w_grid () const
	Access the energy transfer grid points.
double	w_max () const
	Retrieve the maximum ω value.
double	w_min () const
	Retrieve the minimum ω value.

Protected Member Functions
bool	get_neighbor_indices (const std::vector< double > &vec, double val, size_t &lower_index, size_t &upper_index) const

Protected Attributes
std::shared_ptr< std::vector< double > >	qvec_
	Grid points along the q-axis.
std::shared_ptr< std::vector< NuclearResponses > >	responses_
	Sets of nuclear responses evaluated at each grid point.
std::shared_ptr< std::vector< double > >	wvec_
	Grid points along the w-axis.

Detailed Description

A table of nuclear responses for computing inclusive cross sections.

Definition at line 32 of file ResponseTable.hh.

Constructor & Destructor Documentation

ResponseTable() [1/2]

marley::ResponseTable::ResponseTable ( )

inline

Definition at line 35 of file ResponseTable.hh.

{}

ResponseTable() [2/2]

marley::ResponseTable::ResponseTable ( std::shared_ptr< std::vector< double > > & wvec, std::shared_ptr< std::vector< double > > & qvec, std::shared_ptr< std::vector< NuclearResponses > > & resp )

inline

Definition at line 37 of file ResponseTable.hh.

        : wvec_( wvec ), qvec_( qvec ), responses_( resp ) {}

Member Function Documentation

get_neighbor_indices()

bool marley::ResponseTable::get_neighbor_indices ( const std::vector< double > & vec, double val, size_t & lower_index, size_t & upper_index ) const

protected

Determines the indices for the two gridpoints surrounding a requested one-dimensional coordinate. If the coordinate is outside of the grid, then this function returns the two closest grid points.

Parameters

[in]	vec	A vector of grid point coordinates
[in]	val	The requested x or y coordinate
[out]	lower_index	The index of the closest grid point less than or equal to the requested value, or the lower of the two nearest grid points if the value falls outside of the grid
[out]	upper_index	The index of the closest grid point greater than the requested value, or the higher of the two nearest grid points if the value falls outside of the grid

Returns

true if the requested value is within the grid, or false otherwise

Definition at line 61 of file ResponseTable.cc.

{
  if ( vec.size() < 2u ) {
    throw marley::Error( "Vector with fewer than two entries passed to"
      " marley::ResponseTable::get_neighbor_indices()" );
  }
 
  bool within = true;
 
  auto begin = vec.cbegin();
  auto end = vec.cend();
 
  // std::lower_bound returns an iterator to the first element of the
  // container which is not less than the supplied value
  auto not_less_point = std::lower_bound( begin, end, val );
 
  decltype( begin ) lower_point;
 
  // Check whether the requested grid point is within the grid limits
  if ( not_less_point == begin ) {
    lower_point = begin;
    // first element of vec > val
    if ( *begin != val ) within = false;
  }
  else if ( not_less_point == end ) {
    // last element of vec < val
    within = false;
    lower_point = end - 2;
  }
  else {
    // x is within the grid limits
    lower_point = not_less_point - 1;
  }
 
  lower_index = std::distance( begin, lower_point );
  upper_index = lower_index + 1;
 
  return within;
}

Referenced by interpolate().

get_responses()

const std::vector< NuclearResponses > & marley::ResponseTable::get_responses ( ) const

inline

Access the nuclear responses.

Definition at line 61 of file ResponseTable.hh.

        { return *responses_; }

References responses_.

interpolate()

marley::NuclearResponses marley::ResponseTable::interpolate	(	double	w,
		double	q ) const

Use simple bilinear interpolation to compute a set of nuclear responses

Definition at line 20 of file ResponseTable.cc.

{
  // Return a dummy value if the point lies outside the grid boundaries
  if ( w < this->w_min() || w > this->w_max()
    || q < this->q_min() || q > this->q_max() )
  {
    throw marley::Error( "Outside of grid bounds in marley::ResponseTable::"
      "interpolate()" );
    return marley::NuclearResponses();
  }
 
  // Find the indices of the grid points on either side of the desired w and
  // q values.
  size_t iw_low, iw_hi, iq_low, iq_high;
  this->get_neighbor_indices( *wvec_, w, iw_low, iw_hi );
  this->get_neighbor_indices( *qvec_, q, iq_low, iq_high );
 
  // Get the w and q values corresponding to the nearest-neighbor grid
  // points found above
  double w1 = wvec_->at( iw_low );
  double w2 = wvec_->at( iw_hi );
  double q1 = qvec_->at( iq_low );
  double q2 = qvec_->at( iq_high );
 
  // Retrieve the nuclear responses at each of the four grid points of
  // interest
  const auto& r11 = responses_->at( this->response_index(iw_low, iq_low) );
  const auto& r21 = responses_->at( this->response_index(iw_hi, iq_low) );
  const auto& r12 = responses_->at( this->response_index(iw_low, iq_high) );
  const auto& r22 = responses_->at( this->response_index(iw_hi, iq_high) );
 
  // Perform the interpolation (first q, then w)
  NuclearResponses r1 = r11 * (q2 - q)/(q2 - q1) + r12 * (q - q1)/(q2 - q1);
  NuclearResponses r2 = r21 * (q2 - q)/(q2 - q1) + r22 * (q - q1)/(q2 - q1);
  NuclearResponses r  = r1  * (w2 - w)/(w2 - w1) + r2  * (w - w1)/(w2 - w1);
 
  // Return the result
  return r;
}

References get_neighbor_indices(), q_max(), q_min(), qvec_, response_index(), responses_, w_max(), w_min(), and wvec_.

q_grid()

const std::vector< double > & marley::ResponseTable::q_grid ( ) const

inline

Access the 3-momentum transfer grid points.

Definition at line 58 of file ResponseTable.hh.

{ return *qvec_; }

References qvec_.

q_max()

double marley::ResponseTable::q_max ( ) const

inline

Retrieve the maximum q value.

Definition at line 52 of file ResponseTable.hh.

{ return qvec_->back(); }

References qvec_.

Referenced by interpolate().

q_min()

double marley::ResponseTable::q_min ( ) const

inline

Retrieve the minimum q value.

Definition at line 49 of file ResponseTable.hh.

{ return qvec_->front(); }

References qvec_.

Referenced by interpolate().

response_index()

size_t marley::ResponseTable::response_index ( size_t iw, size_t iq ) const

inline

Calculates the index in the vector of responses that corresponds to a given set of ω and q indices

Parameters

[in]	iw	Index of the desired grid point on the ω axis
[in]	iq	Index of the desired grid point on the q axis

Definition at line 68 of file ResponseTable.hh.

                                                                 {
        size_t num_q_points = qvec_->size();
        size_t r_idx = ( num_q_points * iw ) + iq;
        return r_idx;
      }

References qvec_.

Referenced by interpolate().

w_grid()

const std::vector< double > & marley::ResponseTable::w_grid ( ) const

inline

Access the energy transfer grid points.

Definition at line 55 of file ResponseTable.hh.

{ return *wvec_; }

References wvec_.

w_max()

double marley::ResponseTable::w_max ( ) const

inline

Retrieve the maximum ω value.

Definition at line 46 of file ResponseTable.hh.

{ return wvec_->back(); }

References wvec_.

Referenced by interpolate().

w_min()

double marley::ResponseTable::w_min ( ) const

inline

Retrieve the minimum ω value.

Definition at line 43 of file ResponseTable.hh.

{ return wvec_->front(); }

References wvec_.

Referenced by interpolate().

Member Data Documentation

qvec_

std::shared_ptr< std::vector<double> > marley::ResponseTable::qvec_

protected

Grid points along the q-axis.

Definition at line 84 of file ResponseTable.hh.

Referenced by interpolate(), q_grid(), q_max(), q_min(), and response_index().

responses_

std::shared_ptr< std::vector<NuclearResponses> > marley::ResponseTable::responses_

protected

Sets of nuclear responses evaluated at each grid point.

Definition at line 87 of file ResponseTable.hh.

Referenced by get_responses(), and interpolate().

wvec_

std::shared_ptr< std::vector<double> > marley::ResponseTable::wvec_

protected

Grid points along the w-axis.

Definition at line 81 of file ResponseTable.hh.

Referenced by interpolate(), w_grid(), w_max(), and w_min().

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The documentation for this class was generated from the following files:

• /home/sjg/Desktop/marley/include/marley/ResponseTable.hh
• /home/sjg/Desktop/marley/src/ResponseTable.cc