: .M.
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3
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1.
1.1.
. , , . , , . f(x)=0 , :
f(x) [a,b] , f(x) , f(x)=0 .
MathCAD , , . :
1. f(x) , . , .
2. f(x).
3. , , , [ai ,bi] i- .
4. , f(x) f(x). , f(x) 1.5, f(x) 1 ( ).
sf(x):=1.5 sign(f(x) - f(x);
sf1(x):= sign(f1(x) - f(x), f1(x) - f(x).
[ai ,bi] , f(x) , , x, f(x)=0. [ai ,bi] .
1.2.
. , xa xb [ai ,bi], , .
1.2.1.
:
1. xc , [ai ,bi] (.1.) xc = (xa+xb)/2;
2. f(xc) ;
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3. f(xc)× f(xb) > 0, [xc, xb] , , xb= xc ( .1 ). , . [xa, xc] xa= xc ( .1 ).
4. |xb - xa| > e, , .1, , , e.
: , . .
1.2.2.
:
1. xc. , , .. f(xc)× f(xc) > 0. x0 (.2.);
2. xi+1 , xc xi , :
3. |xi+1 xi | > e, , .2, , , e.
, .
1.2.3. ( )
:
1. x0 , , .. f(x0)×f(x0)> 0 (.3.);
2. xi+1 , xi , :
3. |xi+1 xi | > e, , .2, , , e.
: , . : , . .3 , b, x c, [a,b], .
1.2.4.
:
1. f(x)=0 : x=F(x) (1)
2. , 45 x. F(x) f(x)=0(.4.).
3. x0 F(x0) (..4). (1) , x1: x1=F(x0).
4. F(x1), x2=F(x1) . (i+1)- :
xi+1=F(xi ). (2)
5. , |xi+1 xi | > e.
.4, .4) 4) f(x)=0, .4) 4) , x0 . .4) , y=F(x) 45 x, .. F(x)<1. .4) , F(x)>-1. .4) 4) . , :
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|F(x)|<1 (3)
, :
1.
f(x)=0 C: C×f(x)=0 (4)
x: x=x+C×f(x) (5)
(3) , :
|[ x+C×f(x)]|<1,
|1+C×f(x)|<1. (6)
, :
1- : 1+C×f(x)<1, C×f(x)<0; 2- : -1-C×f(x)<1, C×f(x)>-2.
: -2<C×f(x)<0.
C, . f(x) C :
f(x)>0 f(x)<0 (7)
[ai ,bi], , C xa xb C .
2.
.4) 4) , y=F(x), .. . (6) 1+C×f(x)=0, (8)
C [ai ,bi], (8):
(9)
C
C=(Ca+Cb) /2. (10)
, (8) (5) .
x0=(xa+xb) /2.
, , C.
1.3.
root, MathCAD 2001 :
root(f(x),x)
root(f(x),x,a,b)
f(x) - f(x)=0;
x - , ;
a,b - , .
x , , . , , [a,b], .
root TOL, 0.001. //.
2.
f(x)=0, e=0.001.
:
f(x)=0 | f(x)=0 | f(x)=0 | f(x)=0 | ||||
1. | 0.5x+2sin(x)-2=0 | 9. | 0.01x3+cos(x)-0.2=0 | 17. | 15cos(x-0.1)+0.4x3=0 | 25. | x4+(10-x)3+x-600=0 |
2. | x3+(8-x)2-60=0 | 10. | 3cos(x-0.5)+0.4x2=0 | 18. | sin(x)+0.2x2=0 | 26. | sin(x)+cos(2x)+0.8x-3=0 |
3. | 0.2x2+3sin(x)+1=0 | 11. | 0.01x4-2(x-5)2-25x=0 | 19. | (12-sin(x))2-x2-134=0 | 27. | 0.04x3+2(x-4)2-2x-5=0 |
4. | x3-15(x-5)+1=0 | 12. | 5(x-4)4+10(x-5)3+x2=0 | 20. | x4-x3+x2-5=0 | 28. | 4sin(x)-x2+0.2=0 |
5. | 20cos(x)+x3-10=0 | 13. | sin(x2)+5(x+8)-2=0 | 21. | x4+x3-x2-5=0 | 29. | sin(x2)+x+2=0 |
6. | 20cos2(x)+x3-10=0 | 14. | 8sin(x)+2x2-4=0 | 22. | 8cos(x)+x2-4=0 | 30. | 24cos(x-1)+sin(x)+10x-25=0 |
7. | 2cos(x-5)+(x-8)2-2=0 | 15. | 40cos(x-5)+(x-8)3-2=0 | 23. | 5cos(x)+(x-4)2-3=0 | 31. | 10cos(x)+5sin(x)+4x-10=0 |
8. | 10sin(x)+4x-15=0 | 16. | 2sin(x)-x+0.2=0 | 24. | 5cos(x)+(x-8)2-7=0 | 32. | 8cos(x2)+(x-2)3+5x-3=0 |
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2.1. , f(x), f(x) .
2.2. , , .
2.3. root.
2.4.
3.
4.
1. .. . ., ,1975. 632 c.
2. .., .., .. . ., ,1976. 304 .
3. .. : . 2- . ., , 1987.
4. .., .. . ., ,1972.
5. .., .. : . . 2- ., . . -.: , 2002. 304 c.
6. .. . ., ,2003. 192 c.