Function decomposition_band_count

pub fn decomposition_band_count(x_grid: &[f64]) -> usize

Number of grid points falling inside the default μ/y decomposition band [DEFAULT_DECOMP_X_MIN, DEFAULT_DECOMP_X_MAX].

decompose_distortion silently returns mu=y=0 when fewer than three grid points fall in the band, which is the right behaviour for the solver hot loop but a footgun for callers who set a custom (too-narrow) x_min/x_max. Solvers should sample this once at startup and surface a warning before running.