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TriangleProcessor.cxx

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#include "FastShowerUtils/TriangleProcessor.h"

#include <assert.h>
#include <cmath>

namespace FastShower{
  double TriangleProcessor::process(double y) const {
    // example of a left triangle (endPoint1 < endPoint2)
    // Area       : A = m_area
    // lowerLimit : a = m_endPoint1
    // upperLimit : b = m_endPoint2
    // height     : h = 2 * A/(b - a)
    // 
    // distribution function: 
    //     Y' = f(x) = h * (x - a)/(b - a)
    // integral of the above (accumulated distribution):
    //     Y  = F(x) = A * (x - b)**2/(b - a)**2
    // 
    // normalized  :   y = Y/A
    // and inversed:   x = a + (b - a) * y**0.5
    // 
    // NOTE: this is independent of the area!!!
    //

    return m_endPoint1 + (m_endPoint2 - m_endPoint1) * std::sqrt(y);
  }
}//namespace

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