esercizi di matematica con turbo pascal 1.1 su mac

program kramer5;
  (* regola pratica per determinante terzo ordine *)
  (* soluzione sistema a tre equazioni *)
  (* variante di kramer3 .. numeri reali o interi *)
  

  var a1,a2,a3,b1,b2,b3,c1,c2,c3,n1,n2,n3:real;
      ds,dx,dy,dz,x,y,z:real;
      s:string;
      scelta,T:integer;
  

  procedure fine;
  begin
  exit;
  end;
  

  procedure impossibile;
  begin
  writeln('sistema impossibile');
  end;
  

  procedure indeterminato;
  begin
  writeln('sistema indeterminato o impossibile');
  writeln('premi enter');
  readln;
  end;
  

  procedure determinato;
  begin
  writeln('sistema determinato:soluzioni=');
  writeln('determinante sistema   ds=',ds:4:3);
  writeln('determinante incognita dx=',dx:4:3);
  writeln('determinante incognita dy=',dy:4:3);
  writeln('determinante incognita dz=',dz:4:3);
  writeln('X = ',dx/ds:4:3);
  writeln('Y = ',dy/ds:4:3);
  writeln('Z = ',dz/ds:4:3);
  writeln;
  writeln('premi enter');
  readln;
  end;
  

  procedure calcola;
  begin
    clearscreen;
  s:='      ';
  writeln('calcolo determinante terzo ordine:regola di SARRUS ');
  writeln('soluzione sistema con tre equazioni e tre incognite ');
  writeln('scrivi i valori  dei coefficienti e termini noti');
  writeln('se valori con decimali usa punto decimale  5.3  ');
  writeln('dopo ogni valore premere enter ');
  writeln('prova con seguenti valori ');
  writeln('1,2,3,4...2,4,6,8..3,6,9,12       indeterminato ');
  writeln('2,1,2,1...-3,2,-2,2..12,-1,10,4   impossibile ');
  writeln('1,2,3,4...7,3,9,8...2,1,6,3       determinato ');
  writeln('------------------');
  writeln('a1  b1  c1 n1');
  writeln('a2  b2  c2 n2');
  writeln('a3  b3  c3 n3');
  writeln('-------------------');
  write('a1=');readln(a1);
  write('b1=');readln(b1);
  write('c1=');readln(c1);
  write('n1=');readln(n1);
  write('a2=');readln(a2);
  write('b2=');readln(b2);
  write('c2=');readln(c2);
  write('n2=');readln(n2);
  write('a3=');readln(a3);
  write('b3=');readln(b3);
  write('c3=');readln(c3);
  write('n3=');readln(n3);
  writeln('--------------------');
  writeln(a1:4:3,s,b1:4:3,s,c1:4:3,s,n1:4:3);
  writeln(a2:4:3,s,b2:4:3,s,c2:4:3,s,n2:4:3);
  writeln(a3:4:3,s,b3:4:3,s,c3:4:3,s,n3:4:3);
  writeln;
  ds:=a1*b2*c3+b1*c2*a3+c1*a2*b3-a3*b2*c1-b3*c2*a1-c3*a2*b1;
  dx:=n1*b2*c3+b1*c2*n3+c1*n2*b3-n3*b2*c1-b3*c2*n1-c3*n2*b1;
  dy:=a1*n2*c3+n1*c2*a3+c1*a2*n3-a3*n2*c1-n3*c2*a1-c3*a2*n1;
  dz:=a1*b2*n3+b1*n2*a3+n1*a2*b3-a3*b2*n1-b3*n2*a1-n3*a2*b1;
  if (ds<>0) then T:=1 else
  if (ds=0) and (dx=0) and (dy=0) and (dz=0)  then T:=2 else
  if (ds=0) and (dx<>0) or (dy<>0) or (dz<>0) then T:=3 else;
  case T of
  1:determinato;
  2:indeterminato;
  3:impossibile;
  end;
  writeln('-----------------------------------');
  writeln('premi 1 per altro calcolo');
  writeln('premi 2 per finire');
  write('scelta 1 o 2 ? ');readln(scelta);
  case scelta of
  1:calcola;
  2:fine;
  end;
  end;
  

  begin
    clearscreen;
  calcola;
  end.