Function isentropic_density_ratio_kernel 

pub fn isentropic_density_ratio_kernel<R>(
    mach: R,
    gamma: R,
) -> Result<R, PhysicsError>
where
    R: RealField + FromPrimitive,

Isentropic stagnation-to-static density ratio ρ₀/ρ = (1 + (γ−1)/2 · M²)^(1/(γ−1)).

Dimensionless; valid for a calorically perfect gas along an isentrope.

Errors

PhysicsError::PhysicalInvariantBroken unless M is finite and ≥ 0 and γ is finite and > 1 (NaN inputs are rejected).

References

• Anderson, “Modern Compressible Flow: With Historical Perspective,” McGraw-Hill — isentropic flow relations (Ch. 3).