The finite element method obtains the correct solution for any finite element model by. minimizing the energy functional. The minimum of the functional is found by setting the. derivative of the functional with respect to the unknown grid point potential for zero.
Traditionally, 12 days. It goes from Christmas Day, Dec 25, through January 6th, the day of Epiphany. However Its different for different people. For Secular people the secular Christmas lasts usually one or 2 days. However for religious people such as most Christians Christmas actually lasts for 12 days.
The Vatican leaves up their tree and nativity until then. From December 25- February 2 is 40 days. Liturgically, we celebrate an octave of Christmas, which is 8 days. (Just FYI-we also celebrate an octave of Easter starting on Easter Sunday). The octave of Christmas ends on January 1, which is a holy day of obligation (the Solemnity of Mary, the Mother of God.).