function [var_rho]=oct_v2rho_2d(var_v)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Copyright (c) 2000 IRD
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%
% transfert a field at u points to a field at rho points
%
%
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

[N,M,Lp]=size(var_v);
Mp=M+1;
Mm=M-1;
var_rho=zeros(N,Mp,Lp);
var_rho(:,2:M,:)=0.5*(var_v(:,1:Mm,:)+var_v(:,2:M,:));
var_rho(:,1,:)=var_rho(:,2,:);
var_rho(:,Mp,:)=var_rho(:,M,:);

return