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 |