In fact, each B-spline basis function is non-zero on a few adjacent subintervals and, as a result, B-spline basis functions are quite local. Let U be a set of m + 1 non-decreasing numbers, u. The knots can be considered as division points that subdivide the interval [ u. To define B-spline basis functions, we need one more parameter, the degree of these basis functions, p. The i-th B-spline basis function of degree p, written as N. The above is usually referred to as the Cox-de Boor recursion formula. This definition looks complicated; but, it is not difficult to understand.
In 1989, the Griswold family wasn't so lucky in National Lampoon's Christmas Vacation, the third movie in a franchise that included 1983's inaugural Vacation, 1985's European Vacation and 1997's Vegas Vacation..
There has been criticism of the president's vacation at this time. But how does the number of vacation days the president has spent compare to his predecessors? CBS Radio's Mark Knoller has kept track of presidential vacations for years and supplied the data. So far, President Obama has taken 61 vacation days after 31 months in office. At this point in their presidencies, George W. Bush had spent 180 days at his ranch where his staff often joined him for meetings. And Ronald Reagan had taken 112 vacation days at his ranch. Among recent presidents, Bill Clinton took the least time off -- 28 days. To be fair, a presidential vacation away from the White House is not the same as a vacation for the average person. The president is still in contact with his advisers and on call for any emergency. Mark Knoller: When presidents go on vacation, controversy follows