1. Institute of Fundamental Physics and Mathematics, Universidad de Salamanca, Plaza de la Merced 4, 37008 Salamanca, Spain
2. Department of Applied Mathematics, Universidad de Salamanca, Calle del Parque 2, 37008 Salamanca, Spain
3. Department of Economy and Economic History, Universidad de Salamanca, Edificio FES, Campus Miguel de Unamuno, 37007 Salamanca, Spain
4. Sciences and Arts Faculty, Universidad Católica de Ávila (UCAV), Calle Canteros s/n, 05005 Ávila, Spain
5. Research Group on Numerical Simulation and Scientific Calculation, Universidad de Salamanca, 37008 Salamanca, Spain