-- File ball.vhd. Instantiated in top entity Model.
-- Simplified source without discontinuity BREAKs.
-- Use variable step and absolute tolerance 1e-3.

ENTITY Ball IS
  GENERIC ( gravity : REAL := 9.81 );
  PORT ( QUANTITY start, ground :  IN REAL_VECTOR;
         QUANTITY s,v,a         : OUT REAL_VECTOR );
END ENTITY Ball;

ARCHITECTURE Simple OF Ball IS
BEGIN
  BREAK s => start; --Initialization BREAK

  Cycle: FOR i IN 0 TO s'HIGH GENERATE
    IF s(i) > ground(i) -- 'ABOVE not implemented for vector items
    USE
      a(i) == -gravity;
    ELSE 
      a(i) == -gravity - 200.0*v(i) - 10000000.0*( s(i)-ground(i) );
    END USE;
    BREAK ON s(i)'ABOVE( ground(i) ); --Descriptive only
  END GENERATE;
  
  v'DOT == a;
  s'DOT == v;
END ARCHITECTURE Simple;