/** * @brief Extract Q values from vertical dimension of the workspace, or compute * them. * @param workspace workspace possibly containing Q values. */ std::vector<double> FunctionQDepends::extractQValues( const Mantid::API::MatrixWorkspace &workspace) { std::vector<double> qs; // Check if the vertical axis has units of momentum transfer, then extract Q // values... auto axis_ptr = dynamic_cast<Mantid::API::NumericAxis *>(workspace.getAxis(1)); if (axis_ptr) { const boost::shared_ptr<Kernel::Unit> &unit_ptr = axis_ptr->unit(); if (unit_ptr->unitID() == "MomentumTransfer") { qs = axis_ptr->getValues(); } } // ...otherwise, compute the momentum transfer for each spectrum, if possible else { const auto &spectrumInfo = workspace.spectrumInfo(); size_t numHist = workspace.getNumberHistograms(); for (size_t wi = 0; wi < numHist; wi++) { if (spectrumInfo.hasDetectors(wi)) { const auto detID = spectrumInfo.detector(wi).getID(); double efixed = workspace.getEFixed(detID); double usignTheta = 0.5 * spectrumInfo.twoTheta(wi); double q = Mantid::Kernel::UnitConversion::convertToElasticQ(usignTheta, efixed); qs.push_back(q); } else { g_log.debug("Cannot populate Q values from workspace"); qs.clear(); break; } } } return qs; }