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: VBA_IX0.m
    path of file: ./repos/VBA-toolbox/core
    
    the code of the file until where you have to start completion: 
function [IX0,SigmaX0,deltaMuX0,suffStat] = VBA_IX0(X0,y,posterior,suffStat,dim,u,options)
% Gauss-Newton update of initial conditions



if options.DisplayWin % Display progress
    set(options.display.hm(1),'string','VB Gauss-Newton on initial conditions... ');
    set(options.display.hm(2),'string',' ');
    drawnow
end

% check infinite precision transition pdf
iQx0 = VBA_inv(options.priors.iQx{1},options.params2update.x{1},'replace');
IN = diag(~~diag(iQx0));

% Get precision parameters
alphaHat = posterior.a
    
function at current mode
[fx0,dF_dX0] = VBA_evalFun('f',x0,posterior.muTheta,u(:,1),options,dim,1);

% error terms
dx = IN*(posterior.muX(:,1)- fx0);
dx2 = dx'*iQx0*dx;
dx0 = muX0-x0;

% posterior covariance matrix terms
Q = options.priors.SigmaX0(indIn,indIn);
iQ = VBA_inv(Q);
iSigmaX0 = iQ + alphaHat.*dF_dX0(indIn,:)*iQx0(indIn,indIn)*dF_dX0(indIn,:)';

% posterior covariance matrix
SigmaX0 = VBA_inv(iSigmaX0);

% mode
tmp = iQ*dx0(indIn) + alphaHat.*dF_dX0(indIn,:)*iQx0(indIn,indIn)*dx;
deltaMuX0 = SigmaX0*tmp;

% variational energy
IX0 = -0.5.*dx0'*iQ*dx0 - 0.5*alphaHat.*dx2;
if VBA_isWeird (IX0)
    div = 1;
    IX0 = -Inf;
else
    div = 0;
end