1. Department of Mathematics and Statistics, Federal University of Vales Jequitinhonha and Mucuri, Diamantina, Brazil;
2. Statistics Department, Federal University of Minas Gerais, Belo Horizonte, Brazil;
3. Statistics Department, Federal University of Ouro Preto, Ouro Preto, Brazil;
4. Computing Department, Federal University of Ouro Preto, Ouro Preto, Brazil