Scientific applications | Data dimension | Input vector | Constraints |
---|---|---|---|
ToF-SIMS | 3D | 2D (spatial × mass spectrum) | Non-negativity |
STEM (phase analysis by sliding FFT) | 4D | 2D (spatial × FFT spectrum) | Non-negativity |
STM | 3D | 2D (spatial × tunneling spectrum) | Non-negativity, sum to 1 |
X-ray microscopy | 3D or 4D | 2D (spatial × Q spectrum) | Non-negativity, sum to 1, orthogonality |
Raman spectra (AFM) | None | 2D (spatial × Raman spectrum) | Non-negativity |