Fits log10(psd) ~ log10(f) on positive bins; with slope -beta,
returns the 1/f fractal dimension (5 - beta) / 2. Falls back to
1.5 (Brownian) when fewer than two valid bins exist.
Fits log10(psd) ~ log10(f) on positive bins; with slope -beta,
returns the 1/f fractal dimension (5 - beta) / 2. Falls back to
1.5 (Brownian) when fewer than two valid bins exist.