Fixed typo in Silo code.

src/maxwell/maxwell_common.cpp

@@ -290,9 +290,9 @@ export_vector_field_zonal(const model& mod, silo& sdb, const vecxd& Fx,
     std::stringstream expression;
     expression << "{" << Fxname << ", " << Fyname << ", " << Fzname << "}";
 
-    sdb.write_nodal_variable(Fxname.c_str(), out_Fx);
-    sdb.write_nodal_variable(Fyname.c_str(), out_Fy);
-    sdb.write_nodal_variable(Fzname.c_str(), out_Fz);
+    sdb.write_zonal_variable(Fxname.c_str(), out_Fx);
+    sdb.write_zonal_variable(Fyname.c_str(), out_Fy);
+    sdb.write_zonal_variable(Fzname.c_str(), out_Fz);
     sdb.write_vector_expression(field_name.c_str(), expression.str().c_str());  
 }