Function warp_inverse_error 

pub fn warp_inverse_error(
    gamma: &[f64],
    gamma_inv: &[f64],
    argvals: &[f64],
) -> f64

Verify roundtrip accuracy: max |γ(γ⁻¹(t)) - t| over the domain.

Returns the maximum absolute deviation. Values near 0 indicate a high-quality inverse. Typical values for smooth warps: < 1e-10.