Metode Numerik 2 - Universitas Indonesia
Metode Numerik 2 - Universitas Indonesia
Metode Numerik 2 - Universitas Indonesia
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84<br />
Dengan diketahui hanya p(a) dan p(b) (r dan s tidak dicari), maka integrasi<br />
numerik dikerjakan untuk N = 2:<br />
b<br />
2<br />
∫<br />
a<br />
i=<br />
1<br />
p(x) dx = ∑wip(xi<br />
) = w1p(x1<br />
) + w2p(x2<br />
) = w1p(a)<br />
+ w2p(b)<br />
Mencari dan w :<br />
p(x) = r +<br />
w1 2<br />
sx<br />
r(b-<br />
Rumus quadrature trapezoid:<br />
b<br />
∫<br />
a<br />
(r +<br />
1<br />
a) + s(b<br />
2<br />
w<br />
aw<br />
sx) dx<br />
1<br />
1<br />
2<br />
− a<br />
+<br />
I = ∫<br />
2<br />
w<br />
+ bw<br />
b<br />
a<br />
) = r(w<br />
2<br />
2<br />
f(x) dx<br />
= w (r + sa) + w (r + sb)<br />
1<br />
1<br />
= b - a<br />
1<br />
= (b<br />
2<br />
≅<br />
+ w<br />
2<br />
h<br />
2<br />
2<br />
− a<br />
) + s(aw<br />
2<br />
)<br />
2<br />
( f(a) + f(b) )<br />
1<br />
+ bw<br />
2<br />
)<br />
w1 = w2<br />
=<br />
w1 , w2<br />
= ?<br />
(h = b −<br />
1<br />
2<br />
a)<br />
luas trapezoid (lihat gambar)<br />
(b − a)