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Aproximarea functionalelor liniare

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Introducere<br />

Derivare numerică<br />

Integrare numerică<br />

Cuadraturi adaptive<br />

Cuadraturi . . .<br />

Cuadraturi . . .<br />

Formule . . .<br />

Home Page<br />

Title Page<br />

◭◭ ◮◮<br />

◭ ◮<br />

Page 53 of 58<br />

Go Back<br />

Full Screen<br />

Close<br />

Quit<br />

Proprietatea care urmează este baza unui algoritm eficient de<br />

obt¸inere a unor formule de cuadratură gaussiană.<br />

(iv) Fie αk = αk(w) ¸si βk = βk(w) coeficient¸ii din formula de<br />

recurent¸ă pentru polinoamele ortogonale<br />

πk+1(t) = (t − αk)πk(t) − βkπk−1(t), k = 0, 1, 2, . . . (39)<br />

cu β0 definit (ca de obicei) prin<br />

π0(t) = 1, π−1(t) = 0,<br />

b<br />

β0 =<br />

a<br />

w(t)dt (= µ0).<br />

Matricea Jacobi de ordinul n pentru funct¸ia pondere w este o<br />

matrice simetrică tridiagonală definită prin<br />

⎡<br />

α0 √<br />

⎢ β1 ⎢<br />

Jn(w) = ⎢<br />

⎣<br />

√<br />

β1<br />

α1<br />

√<br />

β2<br />

√<br />

β2<br />

. ..<br />

. ..<br />

. ..<br />

0<br />

√ 0<br />

⎤<br />

⎥ .<br />

⎥<br />

βn−1<br />

⎦<br />

√ βn−1 αn−1

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