void FillLinearTrajectory(Position<F> const& initial, Velocity<F> const& velocity, Instant const& t0, Time const& Δt, int const steps, not_null<T<F>*> const trajectory) { for (int i = 0; i < steps; ++i) { Time const iΔt = i * Δt; Displacement<F> const displacement_i = velocity * iΔt; trajectory->Append(t0 + iΔt, DegreesOfFreedom<F>(initial + displacement_i, velocity)); } }