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Lecture 4 - Computer Science Department - University of Kentucky

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We integrate over p(x) as<br />

∫<br />

b<br />

a<br />

f ( x<br />

)<br />

dx ∫ p<br />

( x<br />

)<br />

dx<br />

where we can compute<br />

Gaussian Quadrature<br />

b<br />

≈ ∫ a<br />

n<br />

n<br />

b<br />

= ∑ f ( xi<br />

) ∫ l =<br />

a i ( x)<br />

dx ∑<br />

i=<br />

0<br />

i=<br />

1<br />

i<br />

∫<br />

= b l<br />

a i<br />

A ( x)<br />

dx<br />

A<br />

i<br />

f ( x<br />

Note that the polynomial interpolation is exact for a polynomial <strong>of</strong><br />

degree at most n. It follows that the integration will be exact for such<br />

polynomials<br />

If the nodes can be chosen carefully, it is possible to increase the order<br />

<strong>of</strong> polynomial with the exact integration remarkably. This was<br />

discussed by Karl Gauss<br />

i<br />

)<br />

48

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