atan2: fix output range description

dsp/src/trig.rs

@@ -18,9 +18,9 @@ include!(concat!(env!("OUT_DIR"), "/cossin_table.rs"));
 /// # Returns
 ///
 /// The angle between the x-axis and the ray to the point (x,y). The
-/// result range is from i32::MIN+1 to i32::MAX, where i32::MIN+1
-/// corresponds to an angle of -pi and i32::MAX corresponds to an
-/// angle of +pi.
+/// result range is from i32::MIN to i32::MAX, where i32::MIN
+/// represents -pi and, equivalently, +pi. i32::MAX represents one
+/// count less than +pi.
 pub fn atan2(y: i32, x: i32) -> i32 {
     let mut y = y >> 16;
     let mut x = x >> 16;