solver_nb.solve_firn_heateqn
============================

.. py:function:: solver_nb.solve_firn_heateqn(cell, met_data, dt, dz, fixed_sfc=False, solver_method='hybr')

   Numba-compatible solver function to be used within the model.
   Solves physics.Numba.heateqn.
   This loads in the relevant arguments from the cell, packages them
   into an array form via pack_args, and passes them into the hybrd solver.

   Called in <firn_column>.

   :Parameters: * **cell** (*numpy structured array*) -- Element of the model grid we are operating on.
                * **met_data** (*dict*) -- Dictionary containing the meteorological data for the current timestep.
                  See documentation in firn_column for details.
                * **dt** (*int*) -- Number of seconds in the current timestep [s]
                * **dz** (*float*) -- Size of each vertical point in the cell. [m]
                * **fixed_sfc** (*bool, optional*) -- Boolean flag to determine whether to use the fixed surface form of the
                  heat equation.

   :returns: * **root** (*array_like, float, dimension(core.iceshelf_class.IceShelf.vert_grid)*) -- Vector containing the calculated firn column temperature, either after
               successful completion or
               at the end of the final iteration for an unsuccessful solution. [K]
             * **fvec** (*array_like, float, dimension(core.iceshelf_class.IceShelf.vert_grid)*) -- Vector containing the function evaluated at root, i.e. the raw output.
             * **success** (*bool*) -- Boolean flag determining whether the solution converged, or whether
               there was an error.
             * **info** (*int*) -- Integer flag containing information on the status of the solution.
               From the Minpack hybrd documentation:
               !!  * ***info = 0*** improper input parameters.
               !!  * ***info = 1*** relative error between two consecutive iterates
               !!    is at most `xtol`.
               !!  * ***info = 2*** number of calls to `fcn` has reached or exceeded
               !!    `maxfev`.
               !!  * ***info = 3*** `xtol` is too small. no further improvement in
               !!    the approximate solution `x` is possible.
               !!  * ***info = 4*** iteration is not making good progress, as
               !!    measured by the improvement from the last
               !!    five jacobian evaluations.
               !!  * ***info = 5*** iteration is not making good progress, as
               !!    measured by the improvement from the last
               !!    ten iterations.