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: create_roms_init.m
    path of file: ./repos/tracacode/1911-COAWST/script/mfiles/mtools
    
    the code of the file until where you have to start completion: % script create_roms_init
%
% Create a netcdf file that contains initialization data for ROMS.
% Initializes temp, salt, u, v, ubar, vbar, and 
% all sediment parameters.
%
% In cppdefs.h you should have 
% #undef ana_initial
% #undef ana_sediment
%
% Users can adapt this file to their own application.
%
% jcw 7-8-2008
% jcw 07Feb2012 updated for netcdf mathworks interface
% jcw 19March2015 update to use get_roms_grid
% jcw 28July2
    
function
   Sinp.theta_s     =theta_s;      %surface control parameter
   Sinp.theta_b     =theta_b;      %bottom  control parameter
   Sinp.Tcline      =Tcline;       %surface/bottom stretching width
   Sinp.hc          =hc;           %stretching width used in ROMS
%
   Gout=get_roms_grid(grid_file,Sinp);
%
%6) Initialize zeta, salt, temp, u, v, ubar, vbar.
%
% Init values for zeta.
  display('Initializing zeta')
  if (read_init)
    zeta=ncread(data_file,'zeta',[1 1 tidx],[Inf Inf 1]);
  else
    zeta(1:xi_rho,1:eta_rho,1:length(init_time)) = 0;
  end