diff --git a/test/triqs/det_manip/det_manip_constructors.cpp b/test/triqs/det_manip/det_manip_constructors.cpp
index bf579fde..7b8859a6 100644
--- a/test/triqs/det_manip/det_manip_constructors.cpp
+++ b/test/triqs/det_manip/det_manip_constructors.cpp
@@ -7,13 +7,13 @@
       
       //gives the coefficients of the matrix (function F of the documentation)
       double operator()(double x, double y) const {
-        return(x-y);
+        return (x-y+1)*(x-y);
       }
       
     };
     
     int main() {
-      
+     try { 
       fun f;
       int init_size=10;
       std::vector<double> initial_x{1,2,2.5}, initial_y{3,4,9};
@@ -27,5 +27,6 @@
       //the initial matrix:
       std::cout<<std::endl<< "After construction: D.matrix()=" << D1.matrix()<<std::endl;
       std::cout<<std::endl<< "After construction: D.matrix()=" << D2.matrix()<<std::endl;
-      
-    }
\ No newline at end of file
+     }
+     catch(std::exception const & e ) { std::cout  << "error "<< e.what()<< std::endl;}
+    }