As per the comment from Stennie, the floor and ceiling methods are not supported.
And as per my comment above, the best solution that I could find was just doing an operation that looks like: (num-mod(num,1)) which should yield the same result as the floor function.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…