GaussNoiseProducerFP420 Class Reference

#include <GaussNoiseProducerFP420.h>

Public Member Functions
	GaussNoiseProducerFP420 ()
void	generate (int NumberOfchannels, float threshold, float noiseRMS, std::map< int, float, std::less< int >> &theMap)
	~GaussNoiseProducerFP420 ()

Detailed Description

Definition at line 6 of file GaussNoiseProducerFP420.h.

Constructor & Destructor Documentation

GaussNoiseProducerFP420::GaussNoiseProducerFP420 ( )

inline

Definition at line 8 of file GaussNoiseProducerFP420.h.

{}

GaussNoiseProducerFP420::~GaussNoiseProducerFP420 ( )

inline

Definition at line 9 of file GaussNoiseProducerFP420.h.

References generate(), genParticles_cff::map, and electronIdCutBased_cfi::threshold.

{}

Member Function Documentation

void GaussNoiseProducerFP420::generate	(	int	NumberOfchannels,
		float	threshold,
		float	noiseRMS,
		std::map< int, float, std::less< int >> &	theMap
	)

Definition at line 18 of file GaussNoiseProducerFP420.cc.

References MessageLogger_cfi::cerr, mps_fire::i, createfilelist::int, mps_fire::result, and mps_update::status.

Referenced by GaussNoiseFP420::addNoise(), and ~GaussNoiseProducerFP420().

                                                                                 {
  // estimale mean number of noisy channels with amplidudes above $AdcThreshold$

  // Gauss is centered at 0 with sigma=1
  // Gaussian tail probability higher threshold(=5sigma for instance):
  gsl_sf_result result;
  int status = gsl_sf_erf_Q_e(threshold, &result);
  // MP
  //  if (status != 0) throw DetLogicError("GaussNoiseProducerFP420::could not
  //  compute gaussian tail probability for the threshold chosen");
  if (status != 0)
    std::cerr << "GaussNoiseProducerFP420::could not compute gaussian tail "
                 "probability for the threshold chosen"
              << std::endl;
  float probabilityLeft = result.val;

  // with known probability higher threshold compute number of noisy channels
  // distributed in Poisson:
  float meanNumberOfNoisyChannels = probabilityLeft * NumberOfchannels;
  int numberOfNoisyChannels = CLHEP::RandPoisson::shoot(meanNumberOfNoisyChannels);

  // draw noise at random according to Gaussian tail

  // initialise default gsl uniform generator engine
  static gsl_rng const *const mt19937 = gsl_rng_alloc(gsl_rng_mt19937);

  float lowLimit = threshold * noiseRMS;
  for (int i = 0; i < numberOfNoisyChannels; i++) {
    // Find a random channel number
    int theChannelNumber = (int)CLHEP::RandFlat::shootInt(NumberOfchannels);

    // Find random noise value: random mt19937 over Gaussian tail above
    // threshold:
    float noise = gsl_ran_gaussian_tail(mt19937, lowLimit, noiseRMS);

    // Fill in map
    theMap[theChannelNumber] = noise;
  }
}