Perfect foresight with linear approximation: path for endogenous after...

 Perfect foresight with linear approximation: path for endogenous after failure to converge was not centered

Also add a test for that codepath (linear_approximation + stack_solve_algo=0).

(partial and manually adapted cherry-pick from d2065889)

matlab/perfect-foresight-models/sim1_linear.m

@@ -239,7 +239,7 @@ end
 
 if any(isnan(res)) || any(isinf(res)) || any(isnan(Y)) || any(isinf(Y)) || ~isreal(res) || ~isreal(Y)
     success = false; % NaN or Inf occurred
-    endogenousvariables = reshape(Y, ny, periods+maximum_lag+M_.maximum_lead);
+    endogenousvariables = bsxfun(@plus, reshape(Y, ny, periods+maximum_lag+M_.maximum_lead), steadystate_y);
     if verbose
         skipline()
         if ~isreal(res) || ~isreal(Y)

tests/deterministic_simulations/linear_approximation/sw.mod

@@ -133,3 +133,15 @@ end
 if max(abs(endo_simul_0(:)-endo_simul_1(:)))>.01*options_.dynatol.f
     error('Something is wrong!')
 end
+
+// Test stack_solve_algo=0+linear_approximation, which uses a different codepath than stack_solve_algo=7
+perfect_foresight_setup(periods=300);
+perfect_foresight_solver(linear_approximation, stack_solve_algo=0);
+endo_simul_2 = oo_.endo_simul;
+if ~oo_.deterministic_simulation.status
+   error('Perfect foresight simulation failed')
+end
+
+if max(abs(endo_simul_0(:)-endo_simul_2(:)))>.01*options_.dynatol.f
+    error('Something is wrong!')
+end