------------------------------------------------------------------
--
--  NAME: SQUARE_ROOT - BODY
--  DISCREPANCY REPORTS:
--  
------------------------------------------------------------------
-- file:  square_root_b.ada
-- level: all levels

package body SQUARE_ROOT is

   function SQRT
      (VALUE : float)
   return float is

   -- The function SQRT uses the Newton-Raphson method of finding
   -- the square root.
   --
   -- VALUE - The value used to find the square root.

   R1       : float;
   -- Check for thrashing.

   R0       : float := 1.0;
   -- Initial guess.

   RESULT   : float := ( VALUE + (R0*R0) ) / (2.0 * R0);
   -- The final square root.

   PRECISION : float := 1.0 * 10.0 ** (- float'digits); --float'safe_small;
   -- The most precision expected in the answer.

   begin

      if VALUE < 0.0 then
         raise numeric_error;
      elsif VALUE = 0.0 then
         return(0.0);
      end if;

      loop

         R1 := R0;
         R0 := RESULT;
         RESULT := ( VALUE + (R0*R0) ) / (2.0*R0);

         if (abs ((RESULT-R0)/R0) <= PRECISION) or
            (abs (R1 - RESULT) <= PRECISION) then
            exit;
         end if;

      end loop;

      return RESULT;

   end SQRT;

end SQUARE_ROOT;