From 7aeb881e3ac44efcb051db16d418b47096a7ae2c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?St=C3=A9phane=20Adjemian=20=28Charybdis=29?=
 <stephane.adjemian@univ-lemans.fr>
Date: Sun, 4 Dec 2011 23:57:46 +0100
Subject: [PATCH] Temporarily set the variance of the shocks to zero when
 computing or checking the deterministic steady state. This is necessary if
 the model contains mean preverving spread terms.

---
 matlab/resid.m  |  9 +++++++++
 matlab/steady.m | 11 +++++++++++
 2 files changed, 20 insertions(+)

diff --git a/matlab/resid.m b/matlab/resid.m
index 2e7c47824..91273bb83 100644
--- a/matlab/resid.m
+++ b/matlab/resid.m
@@ -56,6 +56,13 @@ if info(1)
     print_info(info,options_.noprint)
 end
 
+% Keep of a copy of M_.Sigma_e
+Sigma_e = M_.Sigma_e;
+
+% Set M_.Sigma_e=0 (we evaluate the *deterministic* static model)
+M_.Sigma_e = zeros(size(Sigma_e));
+
+
 % Compute the residuals
 if options_.block && ~options_.bytecode
     z = zeros(M_.endo_nbr,1);
@@ -82,6 +89,8 @@ else
                oo_.exo_det_steady_state], M_.params);
 end
 
+M_.Sigma_e = Sigma_e;
+
 
 % Display the non-zero residuals if no return value
 if nargout == 0
diff --git a/matlab/steady.m b/matlab/steady.m
index 93051a749..c9a2272b8 100644
--- a/matlab/steady.m
+++ b/matlab/steady.m
@@ -36,6 +36,14 @@ if options_.steadystate_flag && options_.homotopy_mode
     error('STEADY: Can''t use homotopy when providing a steady state external file');
 end
 
+
+% Keep of a copy of M_.Sigma_e
+Sigma_e = M_.Sigma_e;
+
+% Set M_.Sigma_e=0 (we compute the *deterministic* steady state)
+M_.Sigma_e = zeros(size(Sigma_e));
+
+
 switch options_.homotopy_mode
   case 1
     homotopy1(options_.homotopy_values, options_.homotopy_steps);
@@ -53,6 +61,9 @@ end
 
 disp_steady_state(M_,oo_);
 
+M_.Sigma_e = Sigma_e;
+
+
 if isempty(ys0_)
     oo_.endo_simul(:,1:M_.maximum_lag) = oo_.steady_state * ones(1, M_.maximum_lag);
     %%% Unless I'm wrong, this is (should be?) done in make_y_.m