eflowLookupExp Class Reference

Lookup-table based exponential function to save CPU time, which is used by eflowCellIntegrator. More...

#include <eflowLookupExp.h>

Collaboration diagram for eflowLookupExp:

Public Member Functions
	eflowLookupExp (int nExpBins, int nExpSubBins)
	~eflowLookupExp ()
double	evaluate (double x) const

Static Public Member Functions
static const eflowLookupExp *	getInstance (int nExpBins=50, int nExpSubBins=1000)

Private Attributes
int	m_nExpBins
int	m_nExpSubBins
std::vector< double >	m_exp
std::vector< double >	m_subExp

Detailed Description

Lookup-table based exponential function to save CPU time, which is used by eflowCellIntegrator.

Definition at line 22 of file eflowLookupExp.h.

Constructor & Destructor Documentation

eflowLookupExp()

eflowLookupExp::eflowLookupExp ( int nExpBins, int nExpSubBins )

inline

Definition at line 27 of file eflowLookupExp.h.

                                                :
      m_nExpBins(nExpBins), m_nExpSubBins(nExpSubBins), m_exp(nExpBins+1), m_subExp(nExpSubBins+1) {
    /* Lookup table for the integer part of a number */
    for (int i = 0; i <= nExpBins; ++i) {
      m_exp[i] = exp(-i);
    }
    /* Lookup table for the fractional part of a number */
    const double substep = 1./nExpSubBins;
    for (int iSub = 0; iSub <= nExpSubBins; ++iSub){
      m_subExp[iSub] = exp(-substep* iSub);
    }
  }

~eflowLookupExp()

eflowLookupExp::~eflowLookupExp ( )

inline

Definition at line 40 of file eflowLookupExp.h.

{ }

Member Function Documentation

evaluate()

double eflowLookupExp::evaluate ( double x ) const

inline

Definition at line 42 of file eflowLookupExp.h.

                                  {
    int iExpBin = (int) x;
    int iSubBin(((x-iExpBin)*m_nExpSubBins));
 
    if (iExpBin > m_nExpBins){
      return exp(-x);
    }
    return m_exp[iExpBin]*m_subExp[iSubBin];
  }

getInstance()

const eflowLookupExp * eflowLookupExp::getInstance ( int nExpBins = 50, int nExpSubBins = 1000 )

static

Definition at line 17 of file eflowLookupExp.cxx.

{
  static CxxUtils::CachedUniquePtr<eflowLookupExp> cached ATLAS_THREAD_SAFE;
  if (!cached) {
    cached.set (std::make_unique<eflowLookupExp>(nExpBins, nExpSubBins));
  }
 
  if ( (cached->m_nExpBins != nExpBins) || (cached->m_nExpSubBins != nExpSubBins) )
  {
    throw std::runtime_error("eflowLookupExp: Instance with different bin numbers than existing requested!");
  }
  return cached.get();
}

Member Data Documentation

m_exp

std::vector<double> eflowLookupExp::m_exp

private

Definition at line 55 of file eflowLookupExp.h.

m_nExpBins

int eflowLookupExp::m_nExpBins

private

Definition at line 53 of file eflowLookupExp.h.

m_nExpSubBins

int eflowLookupExp::m_nExpSubBins

private

Definition at line 54 of file eflowLookupExp.h.

m_subExp

std::vector<double> eflowLookupExp::m_subExp

private

Definition at line 56 of file eflowLookupExp.h.

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

• eflowLookupExp.h
• eflowLookupExp.cxx