A-M baby

Task/Fibonacci-sequence/Ada/fibonacci-sequence-1.ada

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+with Ada.Text_IO, Ada.Command_Line;
+
+procedure Fib is
+
+   X: Positive := Positive'Value(Ada.Command_Line.Argument(1));
+
+   function Fib(P: Positive) return Positive is
+   begin
+      if P <= 2 then
+         return 1;
+      else
+         return Fib(P-1) + Fib(P-2);
+      end if;
+   end Fib;
+
+begin
+   Ada.Text_IO.Put("Fibonacci(" & Integer'Image(X) & " ) = ");
+   Ada.Text_IO.Put_Line(Integer'Image(Fib(X)));
+end Fib;

Task/Fibonacci-sequence/Ada/fibonacci-sequence-2.ada

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+with Ada.Text_IO;  use Ada.Text_IO;
+
+procedure Test_Fibonacci is
+   function Fibonacci (N : Natural) return Natural is
+      This : Natural := 0;
+      That : Natural := 1;
+      Sum  : Natural;
+   begin
+      for I in 1..N loop
+         Sum  := This + That;
+         That := This;
+         This := Sum;
+      end loop;
+      return This;
+   end Fibonacci;
+begin
+   for N in 0..10 loop
+      Put_Line (Positive'Image (Fibonacci (N)));
+   end loop;
+end Test_Fibonacci;

Task/Fibonacci-sequence/Ada/fibonacci-sequence-3.ada

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+with Ada.Text_IO, Ada.Command_Line, Crypto.Types.Big_Numbers;
+
+procedure Fibonacci is
+
+   X: Positive := Positive'Value(Ada.Command_Line.Argument(1));
+
+   Bit_Length: Positive := 1 + (696 * X) / 1000;
+   -- that number of bits is sufficient to store the full result.
+
+   package LN is new Crypto.Types.Big_Numbers
+     (Bit_Length + (32 - Bit_Length mod 32));
+     -- the actual number of bits has to be a multiple of 32
+   use LN;
+
+   function Fib(P: Positive) return Big_Unsigned is
+      Previous: Big_Unsigned := Big_Unsigned_Zero;
+      Result:   Big_Unsigned := Big_Unsigned_One;
+      Tmp:      Big_Unsigned;
+   begin
+      -- Result = 1 = Fibonacci(1)
+      for I in 1 .. P-1 loop
+         Tmp := Result;
+         Result := Previous + Result;
+         Previous := Tmp;
+         -- Result = Fibonacci(I+1))
+      end loop;
+      return Result;
+   end Fib;
+
+begin
+   Ada.Text_IO.Put("Fibonacci(" & Integer'Image(X) & " ) = ");
+   Ada.Text_IO.Put_Line(LN.Utils.To_String(Fib(X)));
+end Fibonacci;