Funding for this research was provided by:
Fundação para a Ciência e a Tecnologia (UID/MAT/00324/2013)
Ministerio de Economía y Competitividad (MTM2012-34478)
Fundação para a Ciência e a Tecnologia (FCT IF/00016/2013)
Article History
Received: 16 January 2017
Accepted: 12 May 2017
First Online: 25 May 2017