saving cost-to-go expansion in backward pass

Author: simon-lc

src/solvers/ilqr/backwardpass.jl

@@ -122,6 +122,8 @@ function static_backwardpass!(solver::iLQRSolver2{T,QUAD,L,O,n,n̄,m}) where {T,
 
         # Calculate cost-to-go (using unregularized Quu and Qux)
 		Sxx, Sx, ΔV_ = _calc_ctg!(Q, K_, d_)
+		S[k].xx .= Sxx
+		S[k].x .= Sx
 		ΔV += ΔV_
         k -= 1
     end