/**
* Estimated the FWHM for Gaussian peak fitting
*
*/
void ConvertEmptyToTof::estimateFWHM(const Mantid::MantidVec &spec,
double ¢er, double &sigma,
double &height, double &minX,
double &maxX) {
auto maxValueIt =
std::max_element(spec.begin() + static_cast<size_t>(minX),
spec.begin() + static_cast<size_t>(maxX)); // max value
double maxValue = *maxValueIt;
size_t maxIndex =
std::distance(spec.begin(), maxValueIt); // index of max value
auto minFwhmIt =
std::find_if(MantidVec::const_reverse_iterator(maxValueIt),
MantidVec::const_reverse_iterator(spec.cbegin()),
[maxValue](double value) { return value < 0.5 * maxValue; });
auto maxFwhmIt =
std::find_if(maxValueIt, spec.end(),
[maxValue](double value) { return value < 0.5 * maxValue; });
// double fwhm = thisSpecX[maxFwhmIndex] - thisSpecX[minFwhmIndex + 1];
double fwhm =
static_cast<double>(std::distance(minFwhmIt.base(), maxFwhmIt) + 1);
// parameters for the gaussian peak fit
center = static_cast<double>(maxIndex);
sigma = fwhm;
height = maxValue;
g_log.debug() << "Peak estimate : center=" << center << "\t sigma=" << sigma
<< "\t h=" << height << '\n';
// determination of the range used for the peak definition
size_t ipeak_min = std::max(
std::size_t{0},
maxIndex - static_cast<size_t>(2.5 * static_cast<double>(std::distance(
maxValueIt, maxFwhmIt))));
size_t ipeak_max = std::min(
spec.size(),
maxIndex + static_cast<size_t>(2.5 * static_cast<double>(std::distance(
maxFwhmIt, maxValueIt))));
size_t i_delta_peak = ipeak_max - ipeak_min;
g_log.debug() << "Peak estimate xmin/max: " << ipeak_min - 1 << "\t"
<< ipeak_max + 1 << '\n';
minX = static_cast<double>(ipeak_min - 2 * i_delta_peak);
maxX = static_cast<double>(ipeak_max + 2 * i_delta_peak);
}
