RBC_MoM-test: filter out pathological cases

[skip CI]

tests/estimation/method_of_moments/RBC_MoM_common.inc

@@ -60,7 +60,7 @@ IV_O_N = DELTA*K_O_N;
 Y_O_N = A*K_O_N^(1-ALFA);
 C_O_N = Y_O_N - IV_O_N;
 
-N=RBC_MoM_steady_helper(THETA,ETAl,ETAc,BETTA,B,C_O_N,W);
+[N, info]=RBC_MoM_steady_helper(THETA,ETAl,ETAc,BETTA,B,C_O_N,W);
 C=C_O_N*N;
 Y=Y_O_N*N;
 IV=IV_O_N*N;

tests/estimation/method_of_moments/RBC_MoM_steady_helper.m

-function N = RBC_MoM_steady_helper(THETA,ETAl,ETAc,BETTA,B,C_O_N,W)
+function [N, info]= RBC_MoM_steady_helper(THETA,ETAl,ETAc,BETTA,B,C_O_N,W)
+info=0;
+if ~isreal(C_O_N)
+    info=1;
+    N=NaN;
+    return;
+end
 if ETAc == 1 && ETAl == 1
     N = (1-BETTA*B)*(C_O_N*(1-B))^-1*W/THETA/(1+(1-BETTA*B)*(C_O_N*(1-B))^-1*W/THETA);
 else
     % No closed-form solution use a fixed-point algorithm
     N0 = 1/3;
-    N = fsolve(@(N) THETA*(1-N)^(-ETAl)*N^ETAc - (1-BETTA*B)*(C_O_N*(1-B))^(-ETAc)*W, N0,optimset('Display','off','TolX',1e-12,'TolFun',1e-12));
+    [N, ~, exitflag] = fsolve(@(N) THETA*(1-N)^(-ETAl)*N^ETAc - (1-BETTA*B)*(C_O_N*(1-B))^(-ETAc)*W, N0,optimset('Display','off','TolX',1e-12,'TolFun',1e-12));        
+    if exitflag<1
+        info=1;
+    end
 end
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