Apply Xylar's suggestions from code review

Author: cbegeman

polaris/ocean/tasks/barotropic_gyre/forward.py

@@ -1,5 +1,5 @@
 import time
-from math import ceil
+from math import ceil, floor
 
 from polaris.mesh.planar import compute_planar_hex_nx_ny
 from polaris.ocean.model import OceanModelStep, get_time_interval_string
@@ -124,7 +124,7 @@ def dynamic_model_config(self, at_setup):
         rho_0 = config.getfloat("barotropic_gyre", "rho_0")
 
         dt_max = compute_max_time_step(config)
-        dt = dt_max / 3.
+        dt = floor(dt_max / 3.)
         dt_str = get_time_interval_string(seconds=dt)
 
         options = {'config_dt': dt_str,

polaris/ocean/tasks/barotropic_gyre/init.py

@@ -50,12 +50,12 @@ def setup(self):
         nu_2 = config.getfloat("barotropic_gyre", "nu_2")
 
         # calculate the boundary layer thickness for specified parameters
-        M = (np.pi * 2) / np.sqrt(3) * (nu_2 / beta)**(1. / 3.)
+        m = (np.pi * 2) / np.sqrt(3) * (nu_2 / beta)**(1. / 3.)
         # ensure the boundary layer is at least 3 gridcells wide
-        if M >= 3. * resolution * 1.e3:
+        if m >= 3. * resolution * 1.e3:
             raise ValueError(f"Resolution {resolution} km is too coarse to "
                              "properly resolve the lateral boundary layer "
-                             f"with anticipated width of {(M * 1e-3):03g} km")
+                             f"with anticipated width of {(m * 1e-3):03g} km")
 
         # check whether viscosity suitable for stability
         stability_parameter_max = 0.6