Function einstein_tensor_kernel 

pub fn einstein_tensor_kernel(
    ricci: &CausalTensor<f64>,
    scalar_r: f64,
    metric: &CausalTensor<f64>,
) -> Result<CausalTensor<f64>, PhysicsError>

Calculates the Einstein Tensor: $G_{\mu\nu} = R_{\mu\nu} - \frac{1}{2} R g_{\mu\nu}$.

Arguments

• ricci - Ricci curvature tensor $R_{\mu\nu}$ (Rank 2).
• scalar_r - Ricci scalar $R$.
• metric - Metric tensor $g_{\mu\nu}$ (Rank 2).

Returns

• Ok(CausalTensor<f64>) - Einstein tensor $G_{\mu\nu}$.