You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: landsea.m
    path of file: ./repos/tracacode/1911-COAWST/script/mfiles/rutgers/landmask
    
    the code of the file until where you have to start completion: function [F]=landsea(ncfile, varargin)

% LANDSEA:  Computes and writes ROMS Land/Sea masks
%
% [F]=landsea(ncfile)
% [F]=landsea(ncfile, database)
% [F]=landsea(ncfile, clon, clat)
%
% Computes automatically the Land/Sea mask for an application grid and
% writes it into input NetCDF file. The Land/Sea mask is computed from
% closed coastlines polygoms extracted from the GSHHS dataset.
%
% On Input:
%
%    ncfile      NetCDF file name (string)
%
%    database    GSHHS database (character, OPTIONAL)
%                  'f'    full resolution
%                  'h'    high resolution
%                  'i'    intermediate resolution (default)
%                  'l'    load resolution
%                  'c'    crude resolution
% or
%    clon        Coastline longitude (real vector, OPTIONAL)
%    clat        Coastline latitude  (real vector, OPTIONAL)
%
% On Output:
%
%    F           Land/Sea mask (structure array):
%                  F.mask_rho =>  Mask at rho-points
%                  F.mask_psi =>  Mask at psi-points
%                  F.mask_u   =>  Mask at u-points
%                  F.mask_v   =>  Mask at v-points
%
% Calls:   MEXNC (Interface to NetCDF library using Matlab):
%          nc_dinfo, nc_read, nc_vdef, nc_vnames, nc_write
%
%          r_gshhs, x_gshhs
%
% The masking algorithm is adapted from Charles R. Denham routine
% "domask.m" from the SeaGrid package.
%

% svn $Id: landsea.m 938 2019-01-28 06:35:10Z arango $
%=========================================================================%
%  Copyright (c) 2002-2019 The ROMS/TOMS Group                            %
%    Licensed under a MIT/X style license                                 %
%    See License_ROMS.txt                           Hernan G. Arango      %
%=========================================================================%

Tstart=tic;                         % time profile

extract_coast=false;                % extract coastlines from GSHHS switch

Cfile=which('gshhs_h.b','-ALL');    % select first directory found
DIR=fileparts(Cfile{1});            % others are shadowed

F.ncfile=ncfile;

switch numel(varargin)
  case 0
    extract_coast=true;
    name='gshhs_i.b';               % intermediate resolution
    Cname=fullfile(DIR,name);
    F.Cname=Cname;
  case 1
    extract_coast=true;
    database=varargin{1};
    switch database
      case 'f'                      % full resolution
        name='gshhs_f.b';
      case 'h'                      % high resolution
        name='gshhs_h.b';

    
function [F]=landsea(ncfile, varargin)

% LANDSEA:  Computes and writes ROMS Land/Sea masks
%
% [F]=landsea(ncfile)
% [F]=landsea(ncfile, database)
% [F]=landsea(ncfile, clon, clat)
%
% Computes automatically the Land/Sea mask for an application grid and
% writes it into input NetCDF file. The Land/Sea mask is computed from
% closed coastlines polygoms extracted from the GSHHS dataset.
%
% On Input:
%
%    ncfile      NetCDF file name (string)
%
%    database    GSHHS database (character, OPTIONAL)
%                  'f'    full resolution
%                  'h'    high resolution
%                  'i'    intermediate resolution (default)
%                  'l'    load resolution
%                  'c'    crude resolution
% or
%    clon        Coastline longitude (real vector, OPTIONAL)
%    clat        Coastline latitude  (real vector, OPTIONAL)
%
% On Output:
%
%    F           Land/Sea mask (structure array):
%                  F.mask_rho =>  Mask at rho-points
%                  F.mask_psi =>  Mask at psi-points
%                  F.mask_u   =>  Mask at u-points
%                  F.mask_v   =>  Mask at v-points
%
% Calls:   MEXNC (Interface to NetCDF library using Matlab):
%          nc_dinfo, nc_read, nc_vdef, nc_vnames, nc_write
%
%          r_gshhs, x_gshhs
%
% The masking algorithm is adapted from Charles R. Denham routine
% "domask.m" from the SeaGrid package.
%

% svn $Id: landsea.m 938 2019-01-28 06:35:10Z arango $
%=========================================================================%
%  Copyright (c) 2002-2019 The ROMS/TOMS Group                            %
%    Licensed under a MIT/X style license                                 %
%    See License_ROMS.txt                           Hernan G. Arango      %
%=========================================================================%

Tstart=tic;                         % time profile

extract_coast=false;                % extract coastlines from GSHHS switch

Cfile=which('gshhs_h.b','-ALL');    % select first directory found
DIR=fileparts(Cfile{1});            % others are shadowed

F.ncfile=ncfile;

switch numel(varargin)
  case 0
    extract_coast=true;
    name='gshhs_i.b';               % intermediate resolution
    Cname=fullfile(DIR,name);
    F.Cname=Cname;
  case 1
    extract_coast=true;
    database=varargin{1};
    switch database
      case 'f'                      % full resolution
        name='gshhs_f.b';
      case 'h'                      % high resolution
        name='gshhs_h.b';
      case 'i'                      % intermediate resolution
        name='gshhs_i.b';
      case 'l'                      % low resolution
        name='gshhs_l.b';
      case 'c'                      % crude resolution
        name='gshhs_c.b';
      otherwise
        error(['LANDSEA: illegal GSHHS dataset resolution, ',database])
    end