struktura 0.4.3

Predict failure before it happens. Universal anomaly detection via DFA scaling analysis — spacecraft, bearings, biomedical signals. Zero dependencies.
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# How DFA Works

Detrended Fluctuation Analysis measures long-range correlation in a time series.

## The algorithm in 4 steps

1. **Profile**: compute the cumulative sum of deviations from the mean
2. **Box**: divide the profile into non-overlapping boxes of size *s*
3. **Detrend**: fit and subtract a linear trend within each box
4. **Scale**: measure the root-mean-square residual *F(s)* at each box size

The scaling exponent alpha is the slope of log *F(s)* vs log *s*.

## What alpha means

| Alpha range | Interpretation |
|-------------|---------------|
| ~0.5 | White noise (uncorrelated) |
| 0.5 - 1.0 | Long-range correlated (healthy complexity) |
| ~1.0 | 1/f noise (pink noise) |
| > 1.0 | Non-stationary / trend-dominated |

## Why it works for anomaly detection

Healthy complex systems maintain a characteristic alpha. When the system degrades, alpha shifts — often before any amplitude-based monitor fires. The structure changes first.

## References

1. Peng et al., "Mosaic organization of DNA nucleotide sequences," Physical Review E 49(2), 1994.
2. Peng et al., "Quantification of scaling exponents," Chaos 5(1), 1995.
3. Goldberger et al., "Fractal dynamics in physiology," PNAS 99(suppl 1), 2002.