Quit @D
H** Esercizio 4.3.9 ** L
n = 3;
f @ x_ D := Sum @ a @ k D * x ^ k, 8 k, 0, n <D f @ x D
a @ 0 D + x a @ 1 D + x
2a @ 2 D + x
3a @ 3 D
integrale = Integrate @ f @ x D , 8 x, -1, 1 <D quadratura = f B- 3 3 F + f B 3 3 F integrale - quadratura
2 a @ 0 D + 2 a @ 2 D 3
2 a @ 0 D + 2 a @ 2 D 3 0
H* Era necessario ? * L
f @ x_ D := x ^ 4 f @ x D
integrale = Integrate @ f @ x D , 8 x, -1, 1 <D quadratura = f B- 3 3 F + f B 3 3 F integrale - quadratura
x
42 5 2 9 8 45
H** Esercizio 4.3.10 ** L
n = 3;
f @ x_ D := Sum @ a @ k D * x ^ k, 8 k, 0, n <D f @ x D
a @ 0 D + x a @ 1 D + x
2a @ 2 D + x
3a @ 3 D
h = H b - a L 3;
x @ 0 D = a;
x @ 1 D = a + h;
x @ 2 D = b;
integrale = Integrate @ f @ x D , 8 x, a, b <D quadratura = 3 * h 4 * H 3 * f @ x @ 1 DD + f @ x @ 2 DDL integrale - quadratura
-a a @ 0 D + b a @ 0 D - 1 2
a
2a @ 1 D + 1 2
b
2a @ 1 D - 1 3
a
3a @ 2 D + 1 3
b
3a @ 2 D - 1 4
a
4a @ 3 D + 1 4
b
4a @ 3 D
1
4 H- a + b L a @ 0 D + b a @ 1 D + b
2a @ 2 D + b
3a @ 3 D + 3 a @ 0 D + a +
1
3 H- a + b L a @ 1 D + a + 1
3 H- a + b L
2
a @ 2 D + a + 1
3 H- a + b L
3
a @ 3 D
-a a @ 0 D + b a @ 0 D - 1 2
a
2a @ 1 D + 1 2
b
2a @ 1 D - 1 3
a
3a @ 2 D + 1 3
b
3a @ 2 D -
1 4
a
4a @ 3 D + 1 4
b
4a @ 3 D - 1
4 H- a + b L a @ 0 D + b a @ 1 D + b
2a @ 2 D + b
3a @ 3 D + 3 a @ 0 D + a +
1
3 H- a + b L a @ 1 D + a + 1
3 H- a + b L
2
a @ 2 D + a + 1
3 H- a + b L
3
a @ 3 D Simplify @ integrale - quadratura D
- 1
36 H a - b L
4a @ 3 D
H** Esercizio 4.3.11 ** L
Clear @ f0, f1, f2, b0, b1, b2 D ; f0 @ x_ D := 1;
b0 = Integrate @ f0 @ x D , 8 x, -1, 1 <D f1 @ x_ D := x;
b1 = Integrate @ f1 @ x D , 8 x, -1, 1 <D f2 @ x_ D := x ^ 2;
b2 = Integrate @ f2 @ x D , 8 x, -1, 1 <D 2
0
2 3
Clear @ eq0, eq1, eq2, c0, c1, c2 D ;
eq0 = c0 * f0 @- 1 D + c1 * f0 @ 0 D + c2 * f0 @ 1 D == b0 eq1 = c0 * f1 @- 1 D + c1 * f1 @ 0 D + c2 * f1 @ 1 D == b1 eq2 = c0 * f2 @- 1 D + c1 * f2 @ 0 D + c2 * f2 @ 1 D == b2
c0 + c1 + c2 2 -c0 + c2 0
c0 + c2 2 3
Solve @8 eq0, eq1, eq2 < , 8 c0, c1, c2 <D
:: c0 ® 1 3
, c1 ® 4 3
, c2 ® 1 3 >>
H** Esercizio 4.3.12 ** L
2 Integrazione4.nbClear @ f0, f1, f2, b0, b1, b2 D ; f0 @ x_ D := 1;
b0 = Integrate @ f0 @ x D , 8 x, 0, 2 <D f1 @ x_ D := x;
b1 = Integrate @ f1 @ x D , 8 x, 0, 2 <D f2 @ x_ D := x ^ 2;
b2 = Integrate @ f2 @ x D , 8 x, 0, 2 <D 2
2
8 3
Clear @ eq0, eq1, eq2, c0, c1, c2 D ;
eq0 = c0 * f0 @ 0 D + c1 * f0 @ 1 D + c2 * f0 @ 2 D == b0 eq1 = c0 * f1 @ 0 D + c1 * f1 @ 1 D + c2 * f1 @ 2 D == b1 eq2 = c0 * f2 @ 0 D + c1 * f2 @ 1 D + c2 * f2 @ 2 D == b2 c0 + c1 + c2 2
c1 + 2 c2 2
c1 + 4 c2 8 3
Solve @8 eq0, eq1, eq2 < , 8 c0, c1, c2 <D
:: c0 ® 1 3
, c1 ® 4 3
, c2 ® 1 3 >>
H** Esercizio 4.3.13 ** L
f0 @ x_ D := 1;
b0 = Integrate @ f0 @ x D , 8 x, 0, 1 <D f1 @ x_ D := x
b1 = Integrate @ f1 @ x D , 8 x, 0, 1 <D f2 @ x_ D := x ^ 2
b2 = Integrate @ f2 @ x D , 8 x, 0, 1 <D f3 @ x_ D := x ^ 3
b3 = Integrate @ f3 @ x D , 8 x, 0, 1 <D 1
1 2 1 3 1 4
eq0 = c0 * f0 @ 0 D + c1 * f0 @ x1 D b0 eq1 = c0 * f1 @ 0 D + c1 * f1 @ x1 D b1 eq2 = c0 * f2 @ 0 D + c1 * f2 @ x1 D b2 c0 + c1 1
c1 x1 1 2
c1 x1
2 1 3
Integrazione4.nb 3