/***********************************************************************//**
* @brief Return spatially integrated sky model
*
* @param[in] obsEng Measured photon energy.
* @param[in] obsTime Measured photon arrival time.
* @param[in] obs Observation.
*
* @exception GException::no_response
* No valid instrument response function defined.
*
* Computes
* \f[N"_{\rm pred} = \int_{\rm ROI}
* S(\vec{p}, E, t) PSF(\vec{p'}, E', t' | \vec{d}, \vec{p}, E, t) \,
* {\rm d}\vec{p'}\f]
* where
* \f$S(\vec{p}, E, t)\f$ is the source model,
* \f$PSF(\vec{p'}, E', t' | \vec{d}, \vec{p}, E, t)\f$ is the point
* spread function,
* \f$\vec{p'}\f$ is the measured photon direction,
* \f$E'\f$ is the measured photon energy,
* \f$t'\f$ is the measured photon arrival time,
* \f$\vec{p}\f$ is the true photon arrival direction,
* \f$E\f$ is the true photon energy,
* \f$t\f$ is the true photon arrival time, and
* \f$d\f$ is the instrument pointing.
*
* \f${\rm ROI}\f$ is the region of interest that is stored in the
* GObservation::m_roi member. The integration over the ROI is performed
* by the GResponse::npred() method.
*
* @todo The actual method is only correct if no energy and time dispersion
* exists. For the moment we set srcEng=obsEng and srcTime=obsTime.
* Formally, Equation (2) of the instrument document has to be
* computed, which is an integration over source energy, time
* and arrival direction. For the moment, only the integration over
* arrival direction is performed by GResponse::npred().
***************************************************************************/
double GModelSky::npred(const GEnergy& obsEng, const GTime& obsTime,
const GObservation& obs) const
{
// Initialise result
double npred = 0.0;
// Continue only if model is valid)
if (valid_model()) {
// Get response function
GResponse* rsp = obs.response();
if (rsp == NULL) {
throw GException::no_response(G_NPRED);
}
// Here we make the simplifying approximations
// srcEng=obsEng and srcTime=obsTime. To be fully correct we should
// integrate over true energy and true time here ... at least true
// time if we want to consider energy dispersion ...
GEnergy srcEng = obsEng;
GTime srcTime = obsTime;
// Set source
GSource source(this->name(), *m_spatial, srcEng, srcTime);
// Compute response components
double npred_spatial = rsp->npred(source, obs);
double npred_spectral = spectral()->eval(srcEng);
double npred_temporal = temporal()->eval(srcTime);
// Compute response
npred = npred_spatial * npred_spectral * npred_temporal;
// Compile option: Check for NaN/Inf
#if defined(G_NAN_CHECK)
if (isnotanumber(npred) || isinfinite(npred)) {
std::cout << "*** ERROR: GModelSky::npred:";
std::cout << " NaN/Inf encountered";
std::cout << " (npred=" << npred;
std::cout << ", npred_spatial=" << npred_spatial;
std::cout << ", npred_spectral=" << npred_spectral;
std::cout << ", npred_temporal=" << npred_temporal;
std::cout << ", srcEng=" << srcEng;
std::cout << ", srcTime=" << srcTime;
std::cout << ")" << std::endl;
}
#endif
} // endif: model was valid
// Return npred
return npred;
}
/***********************************************************************//**
* @brief Perform integration over spectral component
*
* @param[in] event Observed event.
* @param[in] srcTime True photon arrival time.
* @param[in] obs Observation.
* @param[in] grad Evaluate gradients.
*
* @exception GException::no_response
* Observation has no valid instrument response
* @exception GException::feature_not_implemented
* Energy integration not yet implemented
*
* This method integrates the source model over the spectral component. If
* the response function has no energy dispersion then no spectral
* integration is needed and the observed photon energy is identical to the
* true photon energy.
*
* @todo Needs implementation of spectral integration to handle energy
* dispersion.
***************************************************************************/
double GModelSky::spectral(const GEvent& event, const GTime& srcTime,
const GObservation& obs, bool grad) const
{
// Initialise result
double value = 0.0;
// Get response function
GResponse* rsp = obs.response();
if (rsp == NULL) {
throw GException::no_response(G_SPECTRAL);
}
// Determine if energy integration is needed
bool integrate = rsp->hasedisp();
// Case A: Integraion
if (integrate) {
throw GException::feature_not_implemented(G_SPECTRAL);
}
// Case B: No integration (assume no energy dispersion)
else {
value = spatial(event, event.energy(), srcTime, obs, grad);
}
// Compile option: Check for NaN/Inf
#if defined(G_NAN_CHECK)
if (isnotanumber(value) || isinfinite(value)) {
std::cout << "*** ERROR: GModelSky::spectral:";
std::cout << " NaN/Inf encountered";
std::cout << " (value=" << value;
std::cout << ", event=" << event;
std::cout << ", srcTime=" << srcTime;
std::cout << ")" << std::endl;
}
#endif
// Return value
return value;
}
/***********************************************************************//**
* @brief Returns spatial model component
*
* @param[in] event Observed event.
* @param[in] srcEng True photon energy.
* @param[in] srcTime True photon arrival time.
* @param[in] obs Observation.
* @param[in] grad Evaluate gradients.
*
* @exception GException::no_response
* Observation has no valid instrument response
*
* This method computes the spatial model component for a given true photon
* energy and arrival time.
***************************************************************************/
double GModelSky::spatial(const GEvent& event,
const GEnergy& srcEng, const GTime& srcTime,
const GObservation& obs, bool grad) const
{
// Initialise result
double value = 0.0;
// Continue only if the model has a spatial component
if (m_spatial != NULL) {
// Get response function
GResponse* rsp = obs.response();
if (rsp == NULL) {
throw GException::no_response(G_SPATIAL);
}
// Set source
GSource source(this->name(), *m_spatial, srcEng, srcTime);
// Get IRF value. This method returns the spatial component of the
// source model.
double irf = rsp->irf(event, source, obs);
// Case A: evaluate gradients
if (grad) {
// Evaluate source model
double spec = (spectral() != NULL) ? spectral()->eval_gradients(srcEng) : 1.0;
double temp = (temporal() != NULL) ? temporal()->eval_gradients(srcTime) : 1.0;
// Set value
value = spec * temp * irf;
// Compile option: Check for NaN/Inf
#if defined(G_NAN_CHECK)
if (isnotanumber(value) || isinfinite(value)) {
std::cout << "*** ERROR: GModelSky::spatial:";
std::cout << " NaN/Inf encountered";
std::cout << " (value=" << value;
std::cout << ", spec=" << spec;
std::cout << ", temp=" << temp;
std::cout << ", irf=" << irf;
std::cout << ")" << std::endl;
}
#endif
// Multiply factors to spectral gradients
if (spectral() != NULL) {
double fact = temp * irf;
if (fact != 1.0) {
for (int i = 0; i < spectral()->size(); ++i) {
(*spectral())[i].gradient((*spectral())[i].gradient() * fact);
}
}
}
// Multiply factors to temporal gradients
if (temporal() != NULL) {
double fact = spec * irf;
if (fact != 1.0) {
for (int i = 0; i < temporal()->size(); ++i) {
(*temporal())[i].gradient((*temporal())[i].gradient() * fact);
}
}
}
} // endif: gradient evaluation has been requested
// Case B: evaluate no gradients
else {
// Evaluate source model
double spec = (m_spectral != NULL) ? m_spectral->eval(srcEng) : 1.0;
double temp = (m_temporal != NULL) ? m_temporal->eval(srcTime) : 1.0;
// Set value
value = spec * temp * irf;
// Compile option: Check for NaN/Inf
#if defined(G_NAN_CHECK)
if (isnotanumber(value) || isinfinite(value)) {
std::cout << "*** ERROR: GModelSky::spatial:";
std::cout << " NaN/Inf encountered";
std::cout << " (value=" << value;
std::cout << ", spec=" << spec;
std::cout << ", temp=" << temp;
std::cout << ", irf=" << irf;
std::cout << ")" << std::endl;
}
#endif
}
} // endif: Gamma-ray source model had a spatial component
// Return value
return value;
}
