Fig. 8: Weights comparison on real PXRD data.

The component weights vs. temperature of the data for (a) MgMn2O4 and (b) tYOCl. The results obtained by a multi-phase Rietveld refinement can be considered as ground-truth and are shown as the dashed purple line. The conventional NMF (red line) cannot capture the temperature evolution of the chemical components. stretchedNMF (green) does much better and sparse-stretchedNMF (blue) yields almost exactly the Rietveld result.