reorder obs/sim parameters in NSE to harmonise with BS/BSS

from now on, obs will always be expected before sim/frc in function signatures

include/evalhyd/deterministic.hpp

@@ -16,23 +16,23 @@ namespace evalhyd
     ///
     /// \tparam A:
     ///     The type of data structures (e.g. `xt::xarray`, `xt::xtensor`).
-    /// \param [in] sim:
-    ///     Array of streamflow simulations.
-    ///     shape: (..., time)
     /// \param [in] obs:
     ///     Array of streamflow observations.
     ///     shape: (1, time)
+    /// \param [in] sim:
+    ///     Array of streamflow simulations.
+    ///     shape: (..., time)
     /// \return
     ///     Array of computed efficiencies.
     ///     shape: (...)
     template <class A>
     inline A nse(
-            const xt::xexpression<A>& sim,
-            const xt::xexpression<A>& obs
+            const xt::xexpression<A>& obs,
+            const xt::xexpression<A>& sim
     )
     {
-        const A& q_sim = sim.derived_cast();
         const A& q_obs = obs.derived_cast();
+        const A& q_sim = sim.derived_cast();
 
         // check that data dimensions are compatible
         if (q_sim.dimension() != q_obs.dimension())