PDF / EILER

1: program EILER; 2:

3:var

4:a,b,x0,y0:real;

5:n1,n2:integer;

7:function F(x,y:real):real;

8:begin

9:F:= -1.180 * y -3.367 * x / y +3.371 * x +2.004;

10:end;

11:

12:procedure Eiler(n:byte);

13:var i:byte;

14:h,x,y,fxy,hfxy:real; {h,x,y,f(x,y),h*f(x,y)}

15:begin

16:h:=(b-a)/n;

17:WriteLn('Число разбиений n=',n,'. Шаг h=',h:5:3);

18:

WriteLn(' N x

y

f(x,y) h*f(x,y) ');

19:WriteLn('------------------------------------');

20:x:=x0;

21:y:=y0;

22:for i:=0 to n do

23:begin

24:fxy:=f(x,y);

25:hfxy:=h*fxy;

26:WriteLn(' ',i:2,' ',x:5:2,' ',y:7:3,' ',fxy:8:3,' ',hfxy:8:3,' ');

27:y:=y+hfxy;

28:x:=x+h;

29:end;

30:WriteLn('------------------------------------');

31:ReadLn;

32:end;

33:

34:begin

35:WriteLn('-- Решение ДУ методом Эйлера --');

36:WriteLn(' интервал [a;b]');

37:Write(' a = '); ReadLn(a);

38:Write(' b = '); ReadLn(b);

39:WriteLn(' начальные условия');

40:Write(' x0 = '); ReadLn(x0);

41:Write(' y0 = '); ReadLn(y0);

42:WriteLn(' число разбиений');

43:Write(' n1 ='); ReadLn(n1);

44:Write(' n2 ='); ReadLn(n2);

45:Eiler(n1);

46:Eiler(n2);

47:end.

48:

49: