Program EYLER;
{$APPTYPE CONSOLE}
Uses
    SysUtils;
{ TODO -oUser -cConsole Main : Insert code here }
const m = 100000;
var i, k, da: integer;
    n, h, t0, t01, y0, eps, emax, e: real;
    yy, y, t: array of real;
Function f(t, y: real): real;   {функция уравнения}
Begin
    f:= -(3 / t) * y  + (6 / (t * y)) - 5 * t;
END;
Begin
    SetLength(y, m);
    SetLength(yy, m);
    SetLength(t, m);
    writeln ('Uravnenie dy / dx = -(3 / t) * y  + (6 / (t * y)) - 5 * t');
    writeln ('Vvedite tochnost` e: '); read(e);
    write ('Vvedite tochku t0: '); readln (t0);
    writeln ('Tochka t01 = ', t0+1);
    t01:= t0 + 1;
    write ('Vvedite shag h: '); readln (h);
    write ('Vvedite nachal`noe znachenie Y(0): '); readln (y0);
    k:= 1;
    while da = 0 do
Begin
    h:= h / k;
    writeln ('Shag h = ', h);
    n:= 1 / h;
    writeln ('Chislo uzlov n = ', n);
    t[0]:= t0;
    y[0]:= y0;
    writeln ('T':15, 'Y':19);
    i:= 1;
    while i <= (n + 1) do
Begin
    y[i]:= y[i-1] + h * f(t[i-1], y[i-1]);  {делаем шаг метода}
    t[i]:= t[i-1] + h;
    i:= i + 1;
END;
    i:= 0;
    while i <= n do
Begin
    writeln (t[i]:15, y[i]:19);
    i:= i + 1;
END;
    h:= h / 2;
    writeln ('Shag h = ', h);
    n:= 1 / h;
    writeln ('Chislo uzlov n = ', n);
    t[0]:= t0;
    yy[0]:= y0;
    writeln ('T':15, 'Y':19);
    i:= 1;
    while i <= (n + 1) do
Begin
    yy[i]:= yy[i-1] + h * f(t[i-1], yy[i-1]);   {делаем шаг метода}
    t[i]:= t[i-1] + h;
    i:= i + 1;
END;
    i:= 0;
    while i <= n do
Begin
    writeln (t[i]:15, yy[i]:19);
    i:= i + 1;
END;
    emax:= 0;
    i:= 1;
    while i <= (n + 1) do
Begin
    eps:= abs(y[i] - yy[1+2*(i-1)]);
    i:= i + 1;
    if eps > emax then
    emax:= eps;
END;
    if emax < e then
Begin
    writeln ('Tochnost` dostignuta.');
    da:= 1;
END
    else
    writeln(' Tochnost` ne dostignuta.');
    k:= k + 1;
END;
    writeln (' Tochnost` dostigaets`a pri shage h = ', h, ' na ', k, '-oy iteracii.');
    readln;
    readln;
END.