EvtItgAbsIntegrator.cpp

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#include "EvtGenModels/EvtItgAbsIntegrator.hh"
 
//-------------
// C Headers --
//-------------
extern "C" {
}
 
#include "EvtGenBase/EvtReport.hh"
 
#include "EvtGenModels/EvtItgAbsFunction.hh"
 
#include <iostream>
#include <math.h>
using std::endl;
 
EvtItgAbsIntegrator::EvtItgAbsIntegrator( const EvtItgAbsFunction& theFunction ) :
    m_myFunction( theFunction )
{
}
 
double EvtItgAbsIntegrator::normalisation() const
{
    return evaluateIt( m_myFunction.lowerRange(), m_myFunction.upperRange() );
}
 
double EvtItgAbsIntegrator::evaluate( double lower, double upper ) const
{
    double newLower( lower ), newUpper( upper );
 
    boundsCheck( newLower, newUpper );
 
    return evaluateIt( newLower, newUpper );
}
 
double EvtItgAbsIntegrator::trapezoid( double lower, double higher, int n,
                                       double& result ) const
{
    if ( n == 1 )
        return 0.5 * ( higher - lower ) *
               ( m_myFunction( lower ) + m_myFunction( higher ) );
 
    int it, j;
 
    for ( it = 1, j = 1; j < n - 1; j++ )
        it <<= 1;
 
    double itDouble( it );
 
    double sum( 0.0 );
 
    double deltaX( ( higher - lower ) / itDouble );
 
    double x( lower + 0.5 * deltaX );
 
    for ( j = 1; j <= it; j++ ) {
        sum += m_myFunction( x );
        x += deltaX;
    }
 
    result = 0.5 * ( result + ( higher - lower ) * sum / itDouble );
 
    return result;
}
 
void EvtItgAbsIntegrator::boundsCheck( double& lower, double& upper ) const
{
    if ( lower < m_myFunction.lowerRange() ) {
        EvtGenReport( EVTGEN_WARNING, "EvtGen" )
            << "Warning in EvtItgAbsIntegrator::evaluate.  Lower bound "
            << lower << " of integral "
            << " is less than lower bound " << m_myFunction.lowerRange()
            << " of function.  No contribution from this range will be counted."
            << endl;
        lower = m_myFunction.lowerRange();
    }
 
    if ( upper > m_myFunction.upperRange() ) {
        EvtGenReport( EVTGEN_WARNING, "EvtGen" )
            << "Warning in EvtItgAbsIntegrator::evaluate.  Upper bound "
            << upper << " of integral "
            << " is greater than upper bound " << m_myFunction.upperRange()
            << " of function.  No contribution from this range will be counted."
            << endl;
        upper = m_myFunction.upperRange();
    }
}