Rollup merge of rust-lang#146451 - DimitriiTrater:atan2_correctness_docs, r=tgross35

Fix atan2 inaccuracy in documentation

Fixes rust-lang#136275

Author: Zalathar

library/std/src/num/f128.rs

@@ -557,10 +557,12 @@ impl f128 {
 
     /// Computes the four quadrant arctangent of `self` (`y`) and `other` (`x`) in radians.
     ///
-    /// * `x = 0`, `y = 0`: `0`
-    /// * `x >= 0`: `arctan(y/x)` -> `[-pi/2, pi/2]`
-    /// * `y >= 0`: `arctan(y/x) + pi` -> `(pi/2, pi]`
-    /// * `y < 0`: `arctan(y/x) - pi` -> `(-pi, -pi/2)`
+    ///  | `x`     | `y`     | Piecewise Definition | Range         |
+    ///  |---------|---------|----------------------|---------------|
+    ///  | `>= +0` | `>= +0` | `arctan(y/x)`        | `[+0, +pi/2]` |
+    ///  | `>= +0` | `<= -0` | `arctan(y/x)`        | `[-pi/2, -0]` |
+    ///  | `<= -0` | `>= +0` | `arctan(y/x) + pi`   | `[+pi/2, +pi]`|
+    ///  | `<= -0` | `<= -0` | `arctan(y/x) - pi`   | `[-pi, -pi/2]`|
     ///
     /// # Unspecified precision
     ///

library/std/src/num/f16.rs

@@ -522,10 +522,12 @@ impl f16 {
 
     /// Computes the four quadrant arctangent of `self` (`y`) and `other` (`x`) in radians.
     ///
-    /// * `x = 0`, `y = 0`: `0`
-    /// * `x >= 0`: `arctan(y/x)` -> `[-pi/2, pi/2]`
-    /// * `y >= 0`: `arctan(y/x) + pi` -> `(pi/2, pi]`
-    /// * `y < 0`: `arctan(y/x) - pi` -> `(-pi, -pi/2)`
+    ///  | `x`     | `y`     | Piecewise Definition | Range         |
+    ///  |---------|---------|----------------------|---------------|
+    ///  | `>= +0` | `>= +0` | `arctan(y/x)`        | `[+0, +pi/2]` |
+    ///  | `>= +0` | `<= -0` | `arctan(y/x)`        | `[-pi/2, -0]` |
+    ///  | `<= -0` | `>= +0` | `arctan(y/x) + pi`   | `[+pi/2, +pi]`|
+    ///  | `<= -0` | `<= -0` | `arctan(y/x) - pi`   | `[-pi, -pi/2]`|
     ///
     /// # Unspecified precision
     ///

library/std/src/num/f32.rs

@@ -827,10 +827,12 @@ impl f32 {
 
     /// Computes the four quadrant arctangent of `self` (`y`) and `other` (`x`) in radians.
     ///
-    /// * `x = 0`, `y = 0`: `0`
-    /// * `x >= 0`: `arctan(y/x)` -> `[-pi/2, pi/2]`
-    /// * `y >= 0`: `arctan(y/x) + pi` -> `(pi/2, pi]`
-    /// * `y < 0`: `arctan(y/x) - pi` -> `(-pi, -pi/2)`
+    ///  | `x`     | `y`     | Piecewise Definition | Range         |
+    ///  |---------|---------|----------------------|---------------|
+    ///  | `>= +0` | `>= +0` | `arctan(y/x)`        | `[+0, +pi/2]` |
+    ///  | `>= +0` | `<= -0` | `arctan(y/x)`        | `[-pi/2, -0]` |
+    ///  | `<= -0` | `>= +0` | `arctan(y/x) + pi`   | `[+pi/2, +pi]`|
+    ///  | `<= -0` | `<= -0` | `arctan(y/x) - pi`   | `[-pi, -pi/2]`|
     ///
     /// # Unspecified precision
     ///

library/std/src/num/f64.rs

@@ -827,10 +827,12 @@ impl f64 {
 
     /// Computes the four quadrant arctangent of `self` (`y`) and `other` (`x`) in radians.
     ///
-    /// * `x = 0`, `y = 0`: `0`
-    /// * `x >= 0`: `arctan(y/x)` -> `[-pi/2, pi/2]`
-    /// * `y >= 0`: `arctan(y/x) + pi` -> `(pi/2, pi]`
-    /// * `y < 0`: `arctan(y/x) - pi` -> `(-pi, -pi/2)`
+    ///  | `x`     | `y`     | Piecewise Definition | Range         |
+    ///  |---------|---------|----------------------|---------------|
+    ///  | `>= +0` | `>= +0` | `arctan(y/x)`        | `[+0, +pi/2]` |
+    ///  | `>= +0` | `<= -0` | `arctan(y/x)`        | `[-pi/2, -0]` |
+    ///  | `<= -0` | `>= +0` | `arctan(y/x) + pi`   | `[+pi/2, +pi]`|
+    ///  | `<= -0` | `<= -0` | `arctan(y/x) - pi`   | `[-pi, -pi/2]`|
     ///
     /// # Unspecified precision
     ///