Hi,
i need to know how to preallocate this "structure" because i need a performance increase ( 8 mins for this is too much to wait), can u help me?

documento=com.mathworks.xml.XMLUtils.createDocument('ospedale');
ospedale=documento.getDocumentElement;
ospedale.setAttribute('azienda',num2str(azienda(1)));

for i=1:length(codice_nosologico) %<----- this is 15901 long
pratica(i)=documento.createElement('pratica');
ospedale.appendChild(pratica(i));
end