Function spacetime_interval_kernel 

pub fn spacetime_interval_kernel(
    x: &CausalMultiVector<f64>,
    metric: &Metric,
) -> Result<f64, PhysicsError>

Calculates the spacetime interval $s^2 = g_{\mu\nu} x^\mu x^\nu$ (squared magnitude in metric).

Arguments

• x - Spacetime vector.
• metric - Expected metric (checked against vector’s internal metric).

Returns

• Ok(f64) - Spacetime interval $s^2$.