Triple world record holder Ian Thorpe of Australia may split with his long-time coach Doug Frost after the Pan Pacific Swimming Championships here, according to reports today.Australian newspapers said 19-year-old Thorpe was considering leaving Frost, who began coaching the swimming superstar when he was an eight-year-old in an outer Sydney suburban swimming pool. Reports said Thorpe, the world’s highest-profile swimmer who is treated like a rock star in Japan, may switch to Tracey Menzies, a young assistant to Frost. The Thorpedo, who won six titles at last year’s World Championships and a record six gold medals at this month’s Manchester Commonwealth Games, has only ever been coached by Frost.