That’s a bad way to compute the adjoint, which is really just solving a linear system. The formula is saying that (1-A)^-1 = sum of A^n, which is a crude way to solve it: a better one is to use an iterative method, as implemented in eg GitHub - JuliaLinearAlgebra/IterativeSolvers.jl: Iterative algorithms for solving linear systems, eigensystems, and singular value problems. The nonlinear case is: solving T = f(T) by Tn+1 = f(Tn) is bad, use something better (eg Anderson acceleration, implemented in JuliaNLSolvers · GitHub)
1 Like