Newton-Cotes formulae
The two methods derived above can be written in the general form
, which is known as a quadrature formula. Typically,
and
. One can derive formulae involving more points in the integration interval. In general, with equidistant points
and
,
and
we call the formula
,
the
point
closed Newton-Cotes formula
when the formula is derived from integrating the Lagrange Polynomial through the data points.
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There also exists open Newton-Cotes formulae where
but these are less accurate and less often used.
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The following Theorem holds:
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Theorem 13
Let us use this idea to define the degree of accuracy or precision of a quadrature formula:
Definition
Some formulae
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