, , .
.
: y = a + bx + cx², : y = eⁿ + x.
, (f (x) = 0).
, f()=0 . , .. , . , .. * ε. , * ε.
:
- ;
- ;
- ;
- .
f (x) a (f (a) < 0), b (f (b) > 0), [a, b] , . . ,
f()= 0.
, f() > 0, f(b) < 0. : b f() . , , . , : =(a + b)/2. f() .
f() . [, ] .
, , , , , , , . [, ] ( f() ). , , , , .
Quicksic, ?
, , , function. b.
, f() f(b) .
:
1. ((f () <= 0) and (f (b) > 0)) or ((f (b) <= 0) and (f (a) > 0))
2. f (a) * f(b) <= 0
, , . :
Do until (b-) < eps... loop
|
|
eps - , , 10ˉ5. f(). , b "": b:=. "" . . , [,d], eps.
, , . f() :
f () = f (0) + f (0)( x0)
:
f (x) = 0, xi = xi+1 f (x0)/f ' (x0)
, , , , . , :
x1 = x0 f (x0)/ f ' (x0)
x2 = x1 f (x1)/ f ' (x1)
xi+1 = xi f (xi)/ f ' (xi)
? : :
| f (x)| < eps, :
| f (x)/ f '(x)| < eps
| Xi+1 Xi| <= eps
. f() = 0 φ()=, g()=f(x). 0 , φ(x)≠0, x0 .
φ(x)=x1 . φ(1) 2 (2 = φ(x1) .., i+1 =φ(i). 0, x1, 2, 3, 4, * (. 1.a).
|φ(x)| <= 1 [,b], , , . ( ).
2 ,
. , 0, x1, 2,
*. , φ(x) .
f(x) = 0 φ(x) = x; , .
:
f(x) + x = 0 + x, f(x) + x = φ(x)
() | () | () |
) 0 < φ() < 1; | ) 1 < φ() < 0 | |
P.6 |
. , φ()=-f()/, k ,
|k| >Q/2, Q=m |f'()| f'() [, b].
|x* - xi| <= (q/(1 q))*|X(i) X(i+1)|, q = max φ(), [a,b].
|
|
(q/(q 1))*|X(i) X(i + 1)|<= ε, ε .
|X(i) X(i + 1)|<=ε , (.. ).
4).
f() [, b]
, ,
. , (, f(a)) (b,f(b)). = + d, , = 0 . , x1 ,
, . (x1, f(x1)) , 2 .. , 3, 4,5,..., .
.
f(). f(b)*f (b) > 0, ("") , :
xi+1=xi-(f(xi)/(f(b)-f(xi)))*(b-xi);
1,2,, .
f()f"() > 0, ("") , : xi+1 = a +(f(a) / (f(a) f(xi)))*(xi a);
.7 |
1,2, .
7 . "" . ( ), .
, f() 2 , |* - i| < |i i-1| |i+1 - i| <= ε, xi+1 ( f(i) <= δ, ). , .
1. , (F(x) = 0), (a, b), (eps) , ( ) .
2. , : , ).
3. , :
(f()- f"() > 0), , - .
4. F().
5. , .
6. , , .
7. F(x) ( ).
8. .
9. .
10. .