(
  Codigo em LikeForth
)


: inverte (a b c -- c b a) SWAP 2 ROLL ;



: delta (a b c -- SQRT(b * b - 4 * a * c))
  SWAP DUP *   ( a b c -> b*b a c)
  ROT * 4 *    ( -> 4*a*c b*b )
  -            ( -> b*b - 4*a*c )
  DUP
  0 < NOT
  IF
    SQRT       ( se delta >= 0, SQRT(delta) )
  ELSE
    DROP -1    ( senao deixa soh -1 na pilha )
  THEN
;

: raiz1 (a b c -- -b/2a ) 2 * SWAP -1 * / ;




: raiz2  (a b c -- (-b+-SQRT(b*b-4*a*c))/2a )
  DUP 2 *
  3 ROLL 3 ROLL 3 ROLL
  1 PICK
  -1 *
  3 ROLL 3 ROLL 3 ROLL
  delta
  SWAP
  1 PICK 1 PICK
  SWAP - >R
  SWAP + >R
  DUP R> SWAP / SWAP
  R> SWAP /
;







: raizes ( a b c -- 0,1ou2 raizes na pilha )
  3 DO 2 PICK LOOP
  delta
  DUP 0 =
  IF           ( se delta == 0, 1 raiz )
    DROP raiz1
    SWAP DROP
  ELSE
    0 >
    IF         ( se delta > 0, 2 raizes )
      raiz2
    ELSE       ( senao, pilha vazia )
      BEGIN DROP EMPTY UNTIL
    THEN
  THEN
;








(--
  Le 3 valores do teclado e resolve
    a eq de 2o grau correspondente.
    Marco Cristo, 2014, Compiladores
--)

."valor de a: " ?
."valor de b: " ?
."valor de c: " ?
inverte
raizes

EMPTY
IF
  ."Nao ha solucoes!" CR
ELSE
  ."Raiz 1: " . CR
  EMPTY NOT
  IF
    ."Raiz 2: " . CR
  THEN
THEN