Cetacea Cetacea Cetacea () is a widely distributed and diverse clade of aquatic mammals that today consists of whales, dolphins, and porpoises. Cetaceans are carnivorous and finned. Most species live in the sea, some in rivers. The name is derived from the Latin "cetus" "whale", itself from the Greek κῆτος "kētos" "huge fish". There are around 89 extant species, which are divided into two groups or parvorders, the Odontoceti or toothed whales, a group of more than 70 species that includes the dolphins, porpoises, belugas, narwhals, sperm and beaked whales, and the Mysticeti or baleen whales, of which there are now
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