.
: , .
[a,b], (.4.1), n (n = 4), xi = a+h*i-h/2; h = (b-a)/n.
si=h*f(xi). si : .
, , . n , .. n = 2n. .
.4.1
e, |S1 - S2|<e. , S2 ; , S2 , .. S1 = S2. S2. n S2 , S1 S2 e.
4.1. .
#include <iostream>
#include <conio.h>
#include <math.h>
using namespace std;
#define Pi 3.14159
int main()
{unsigned long i, n = 4;
float a,b,x,h,S1,S2,eps,exact;
a = 0; b = 3/(2*Pi); eps = 0.001;
S1 = 0;
h = (b a)/n;
//
for (i = 1; i<=n; i++)
{ x = a + i*h h/2;
S1 = S1+ (1/(53*cos(x)))*h;
}
//
do {n = 2*n;
h = (b a)/n;
S2 = 0;
for (i = 1; i<=n; i++)
{x = a + i*h h/2;
S2 = S2 + (1/(53*cos(x)))*h;
}
exact = fabs(S1 S2);
S1 = S2;
} while(exact>eps);
cout << "S = " << S2;
return 0;
}
[a,b]
, (.4.2). a b - ; xi = a + i(b - a)/n.
[a,b] n () .
:
n - ; xi = a + i(b a)/n.
f(xi). f(a) f(b) , 4, - 2. .
.4.2. .
4.2. .
|
|
#include <iostream>
#include <conio.h>
#include <math.h>
using namespace std;
int main()
{unsigned long i, n;
float a,b,x,h,y,s;
cout << " -> ";
cin >> n;
a = 0; b = 1.8;
s = 0; x = a;
h = (b a)/n;
for (i = 0; i <= n; i++)
{ y = (1/(1+sqrt(x));
x = x + h;
if (i % 2!= 0) s = s + 4*y;
else if (i == 0 || i == n) s = s + y;
else s = s + 2*y;
}
s*=h/3;
cout << "S = " << s;
}
e F(x)=0
[a,b] (.4.3). F(x) = 0 x = f(x). x = x1, x = f(x), x2 = f(x1).
x3 = f(x2),..., xk+1 = f(xk).
, |f(x)|<1 , . 1<f ΄(x)<0, [xk, xk+1] [xk+1,xk] [xk+1 xk]<e.
.4.3.
F(x) = 0 f(x) . F(x) = 0 h x. :
hF(x) + x = 0*h + x;
hF(x) + x = x.
f(x) = hF(x) + x, x = f(x). h , |f '(x)|<1, f '(x)<0 , .
, , . |xg x t|<e, xt
4.3. .
.
#include <iostream>
#include <conio.h>
#include <math.h>
using namespace std;
int main()
{ float xt, xg = 2.3, eps = 0.001, x = 5*eps;
int step = 0;
while (fabs(x)>=eps)
{ xt = -0.2*(xg*xg*xg 2*xg*xg 3)+xg;
x = xt-xg;
step++;
xg = xt;
}
cout << " = " << xt << " " << step;
getch();
return 0;
}
f(x) = 0 e