Merge pull request #513 from JohannesPfeifer/improved_messages

Add more explicit information in case of singularity problem

matlab/model_diagnostics.m

@@ -85,6 +85,7 @@ end
 %
 % singular Jacobian of static model
 %
+singularity_problem = 0;
 if ~isfield(M,'block_structure_stat')
     nb = 1;
 else
@@ -107,6 +108,7 @@ for b=1:nb
     end
     rank_jacob = rank(jacob);
     if rank_jacob < size(jacob,1)
+        singularity_problem = 1;
         disp(['model_diagnostic: the Jacobian of the static model is ' ...
               'singular'])
         disp(['there is ' num2str(endo_nbr-rank_jacob) ...
@@ -143,4 +145,9 @@ for b=1:nb
         end
     end
 end
+if singularity_problem 
+    fprint('The presence of a singularity problem typically indicates that there is one\n')
+    fprint('redundant equation entered in the model block, while another non-redundant equation\n')
+    fprint('is missing. The problem often derives from Walras Law.\n')
+end
 

matlab/print_info.m

@@ -36,7 +36,8 @@ if ~noprint
       case 2
         error(['The generalized Schur (QZ) decomposition failed. ' ...
                'For more information, see the documentation for Lapack function dgges: info=' ...
-               int2str(info(2)) ', n=' int2str(info(3))])
+               int2str(info(2)) ', n=' int2str(info(3)) ...
+               '. You can also run model_diagnostics to get more information on what may cause this problem.'])
       case 3
         error(['Blanchard Kahn conditions are not satisfied: no stable' ...
                ' equilibrium'])