LXL Lyl = 1,

LXL Lyl = 1,

Easy to know: | x | & gt; = 1,
(1) When X & gt; = 1, Y & gt; = 0, y = X-1
(2) When X & gt; = 1, Y & lt; 0, y = - x + 1
(3) When X & lt; = - 1, Y & gt; = 0, y = - X-1
(4) When X & lt; = - 1, Y & lt; 0, y = x + 1