function []= LogMsg(msg, fileName)

logDir = '_Log/';
if isdir(logDir) == 0
    mkdir(logDir);
end

if nargin<2
    fileName = 'log.txt';
end

fullFileName = sprintf('%s%s',logDir,fileName);
fileID = fopen(fullFileName,'a');
fprintf(fileID,'%s\n',msg);
fprintf('%s\n',msg);
fclose(fileID);