program pierwiastek;
begin
pref IIUWgraph block
const
   aspekt=1.33333333333,
   Pi=3.1415926536,
   jednostka=25;
(*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*)
 unit WaitMoment:procedure;
 var r:integer;
   begin
     call move(290,320);
     call outstring("Press any key!");
     while r = 0 do
       r:=inkey
     od;
     call move(290,320);
     call outstring("       *      ");
 end WaitMoment;
(*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*)
unit punkt:class(x,y:real);
  unit plot:procedure;
  begin
    call move(round(x*aspekt)-3,round(y));
    call draw(round(x*aspekt)+3,round(y));
    call move(round(x*aspekt),round(y)-2);
    call draw(round(x*aspekt),round(y)+3);
  end plot;
end punkt;

(*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*)

unit okrag :class (S:punkt;r:real);
  unit cirb:procedure(alfa,beta:real);
  var gamma,x,y:real;
  begin
    if alfa<beta then
          gamma:=alfa
    else  gamma:=beta;
          beta:=alfa
    fi;
    x:=round(aspekt*(S.x+(r*cos(gamma))));
    y:=round(S.y+(r*sin(gamma)));
    call move(x,y);
    while gamma<=beta do
      x:=round(aspekt*(S.x+(r*cos(gamma))));
      y:=round(S.y+(r*sin(gamma)));
      call draw(x,y);
      gamma:=gamma+0.01
    od
  end cirb;
  unit rys:procedure(A:punkt);
  var alfa,pom:real;
  begin
  pom:=(A.y-S.y)/(A.x-S.x);
  alfa:=atan(pom);
  if A.x-S.x<0 then
       alfa:=Pi+alfa
  fi;
  call cirb(alfa-0.3,alfa+0.3);
  end rys;
end okrag;

(*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*)

unit odcinek:class(A,B:punkt);
begin
call move(round(A.x*aspekt),round(A.y));
call draw(round(B.x*aspekt),round(B.y))
end odcinek;

(*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*)

unit odleglosc:function(A,B:punkt):real;
begin
  result:=sqrt((B.x-A.x)*(B.x-A.x)+(B.y-A.y)*(B.y-A.y))
end odleglosc;

(*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*)

unit srodek_odcinka:function(GH:odcinek):punkt;
    var
     o2,o3:okrag,
     C,D:punkt,
     CD:odcinek;
begin
   o2:=new okrag(GH.A,odleglosc(GH.A,GH.B));
   o3:=new okrag(GH.B,odleglosc(GH.A,GH.B));
   call okrag_okrag(o2,o3,C,D);
   call WaitMoment;
   CD:=new odcinek(C,D);
   result:=odcinek_odcinek(GH,CD)
end srodek_odcinka;
(*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*)

unit okrag_okrag:procedure(o2,o1:okrag;output G,H:punkt);
var
   ax2,ay2,cx2,cy2,r12,r22:real,
   A,B:punkt,
   AB:odcinek;
begin
   ax2:=o1.S.x * o1.S.x;
   ay2:=o1.S.y * o1.S.y;
   cx2:=o2.S.x * o2.S.x;
   cy2:=o2.S.y * o2.S.y;
   r12:=o1.r * o1.r;
   r22:=o2.r * o2.r;
  A:=new punkt(0,(r12-r22-ay2-ax2+cx2+cy2)/(2*(o2.S.y-o1.s.y)));
B:=new punkt(1,(r12-r22-ay2-ax2+cx2+cy2+2*o1.s.x-2*o2.s.x)/(2*(o2.S.y-o1.s.y)));
  AB:=new odcinek(A,B);
  call okrag_odcinek(o1,AB,G,H);
  call o1.rys(G);
  call o2.rys(G);
  call G.plot;
  call outstring("G");
  call o1.rys(H);
  call o2.rys(H);
  call H.plot;
  call outstring("H");
end okrag_okrag;

(*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*)

unit okrag_odcinek:procedure(o:okrag;p:odcinek;output G,H:punkt);
var
   a,b,c,x,y,delta,m:real;
begin

   m:=(p.B.y - p.A.y) / (p.B.x - p.A.x);
   a:=(m * m) + 1;
   b:=(-2) * ((m * m * p.A.x) - (m * p.A.y)+(o.s.x)+(m*o.s.y));
   c:=m * p.A.x *(m * p.A.x - 2 * p.A.y) + (p.A.y * p.A.y) - (o.r * o.r);
   c:=c+(o.s.x*o.s.x)+(o.s.y*o.s.y)-(2*p.a.y*o.s.y);
   c:=c+(2*m*p.a.x*o.s.y);
   delta :=b * b -(4 * a * c);
   if delta < 0 then
                G:=none;
                H:=none;
   else
      if delta = 0 then
                   x:= -b / (2 * a);
                   y:= m *(x - p.A.x) + p.A.y;
                   G:=new punkt(x ,y);
      else       delta:=sqrt(delta);
                 x:= (-b - delta) / (2 * a);
                 y:= m *(x - p.A.x) + p.A.y;
                 G:=new punkt(x ,y);
                 x:= (-b + delta) / (2 * a);
                 y:= m *(x - p.A.x) + p.A.y;
                 H:=new punkt(x ,y);
      fi
   fi
end okrag_odcinek;


(*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*)

unit  punkt_odlegly:function(AB:odcinek;odl:integer):punkt;
(*   Funkcja zwraca punkt odlegly w poziomie o odl lezacy na prostej AB.   *)
var
  G,H:punkt,
  o:okrag;
begin
  o:=new okrag(AB.B,odl*jednostka);
  call okrag_odcinek(o,AB,G,H);
  if odleglosc(AB.A,G)<odleglosc(AB.A,H) then
    result:=H
  else
    result:=G
  fi
end punkt_odlegly;

(*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*)

unit odcinek_odcinek:function(AB,CD:odcinek):punkt;
var
   m1,m2,x,y:real;
begin
   m1:=(AB.B.y-AB.A.y)/(AB.B.x-AB.A.x);
   m2:=(CD.B.y-CD.A.y)/(CD.B.x-CD.A.x);
   x:=(m1*AB.A.x-AB.A.y-m2*CD.A.x+CD.A.y)/(m1-m2);
   y:=m1*(x-AB.A.x)+AB.A.y;
   result:=new punkt(x,y)
end odcinek_odcinek;

(*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*)

unit prostopadla:function(AC:odcinek;B:punkt):odcinek;
var
  o1,o2,o3:okrag,
  G,H,K,L:punkt;
begin
o1:=new okrag(B,odleglosc(B,AC.B));
call okrag_odcinek(o1,AC,G,H);
o2:=new okrag(G,2*odleglosc(B,AC.B));
o3:=new okrag(H,2*odleglosc(B,AC.B));
call okrag_okrag(o2,o3,K,L);
result:=new odcinek (K,L)
end prostopadla;

(*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*)



var
   A,B,C,D,E,F,G:punkt,
   o1:okrag,
   AC,AB,BE,BF:odcinek,
   wynik:real;
begin

   call gron(0);
   A:=new punkt(200,100);
   call A.plot;
   call outstring ("A");
   call move (100,300);
   call outstring("Choose second point and press <END>.");
   call track(303,202);
   B:=new punkt(inxpos*(1/aspekt),inypos);
   call B.plot;
   call outstring ("B");
   call move (100,300);
   call outstring("                                    ");
   AB:=new odcinek(A,B);
   C:=punkt_odlegly(AB,1);
   call C.plot;
   call outstring ("C");
   AC:=new odcinek(A,C);
   call WaitMoment;
   D:=srodek_odcinka(AC);
   call D.plot;
   call outstring("D");
   call WaitMoment;
   o1:=new okrag(D,odleglosc(D,C));
   call cirb(round(D.x*aspekt),round(d.y),round(odleglosc(D,C)*aspekt),1,1,1,0,1,1);
   BE:=prostopadla(AC,B);
   call WaitMoment;
   call okrag_odcinek(o1,BE,F,G);
   wynik:=odleglosc(B,F);
   call F.plot;
   call outstring("F");
   BF:=new odcinek(B,F);
   call move(100,310);
   call outstring("Dlugosc odcinka BF wynosi pierwiastek z dlugosci odcinka AB.");
   call WaitMoment;
   call groff
 end
end.