             fp[I_q] -= gupdate;
         }
     }
-    //__syncthreads();
+    __syncthreads();
 
     /*  transverse-y
     

            gp[I_q] -= gupdate;
        }
    }
    //__syncthreads();


    /*     transverse-x

            gp[I_q - 1] -= gupdate;   
        }            
    }
    __syncthreads();


    /*     transverse-x
