returns fibonacci sequence in pl/pgsql

fibonacci.plpgdql

CREATE OR REPLACE FUNCTION fibonacci(num integer)
	RETURNS SETOF numeric AS $$
DECLARE
a numeric := 0;
b numeric := 1;
BEGIN
IF (num <= 0)
THEN RETURN;
END IF;
RETURN NEXT a;
LOOP
EXIT WHEN num <= 1;
RETURN NEXT b;
num = num - 1;
SELECT b, a + b INTO a, b;
END LOOP;
END;
$$ language plpgsql;