Lagrange's interpolation formula
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English[edit]
Etymology[edit]
Named after Joseph Louis Lagrange (1736–1813), an Italian Enlightenment Era mathematician and astronomer.
Noun[edit]
Lagrange's interpolation formula (uncountable)
- (mathematics) A formula which when given a set of n points , gives back the unique polynomial of degree (at most) n − 1 in one variable which describes a function passing through those points. The formula is a sum of products, like so: . When then all terms in the sum other than the i th contain a factor in the numerator, which becomes equal to zero, thus all terms in the sum other than the i th vanish, and the i th term has factors both in the numerator and denominator, which simplify to yield 1, thus the polynomial should return as the function of for any i in the set .