Metode Numerik 2 - Universitas Indonesia
Metode Numerik 2 - Universitas Indonesia
Metode Numerik 2 - Universitas Indonesia
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62<br />
Secara umum, untuk N data<br />
rumus interpolasi Lagrange:<br />
Untuk x = x (k = 1, …, N):<br />
k<br />
l(x , x ) =<br />
k<br />
i<br />
∏<br />
⎛ x<br />
⎜<br />
⎝<br />
x<br />
k<br />
− x<br />
− x<br />
j<br />
j≠i i j<br />
p(x) =<br />
l(x, x )<br />
i<br />
N<br />
∑<br />
i=<br />
1<br />
⎧ ⎛ x ⎞ i − xj<br />
⎪∏⎜<br />
⎟<br />
⎞ ⎪<br />
⎜ ⎟<br />
j≠i ⎝<br />
xi<br />
− xj<br />
⎟ =<br />
⎠<br />
⎟<br />
⎨<br />
⎠ ⎪ ⎛ ⎞<br />
⎜<br />
xk<br />
− xk<br />
⎟<br />
⎪<br />
... ...<br />
⎜ ⎟<br />
⎩ ⎝<br />
xi<br />
− xj<br />
⎠<br />
l(xk , xi)<br />
= δik<br />
p(xk<br />
) = f(xk<br />
)<br />
l(x, x )f(x )<br />
⎛<br />
j<br />
= ∏⎜ ⎜<br />
j≠i xi<br />
− xj<br />
⎝<br />
i<br />
= 1,<br />
= 0,<br />
x − x<br />
i<br />
⎞<br />
⎟<br />
⎠<br />
(i = k)<br />
(i ≠ k)