Cetacea toothed whales and two in baleen whales. The nostrils are located on top of the head above the eyes so that the rest of the body can remain submerged while surfacing for air. The back of the skull is significantly shortened and deformed. By shifting the nostrils to the top of the head, the nasal passages extend perpendicularly through the skull. The teeth or baleen in the upper jaw sit exclusively on the maxilla. The braincase is concentrated through the nasal passage to the front and is correspondingly higher, with individual cranial bones that overlap. In toothed whales, connective tissue
Divided differences "ƒ" on the nodes "x", ..., "x" are used: etc. Divided differences for formula_12 and the first few values of formula_13: To make the recursive process more clear, the divided differences can be put in a tabular form: The divided difference scheme can be put into an upper triangular matrix. Let formula_24. Then it holds formula_44 With the help of a polynomial function formula_45 with formula_46 this can be written as Alternatively, we can allow counting backwards from the start of the sequence by defining formula_48 whenever formula_49 or formula_50. This definition allows formula_51 to be interpreted as formula_52, formula_53