Update comments for {f16, f32, f64, f128}::midpoint

Clarify what makes some operations not safe, and correct comment in the default branch ("not safe" -> "safe").
rust-lang · Aug 1, 2024 · 4383642 · 4383642
1 parent e18036c
commit 4383642
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Showing 4 changed files with 12 additions and 12 deletions.
diff --git a/library/core/src/num/f128.rs b/library/core/src/num/f128.rs
@@ -851,13 +851,13 @@ impl f128 {
             // Overflow is impossible
             (a + b) / 2.
         } else if abs_a < LO {
-            // Not safe to halve a
+            // Not safe to halve `a` (would underflow)
             a + (b / 2.)
         } else if abs_b < LO {
-            // Not safe to halve b
+            // Not safe to halve `b` (would underflow)
             (a / 2.) + b
         } else {
-            // Not safe to halve a and b
+            // Safe to halve `a` and `b`
             (a / 2.) + (b / 2.)
         }
     }

diff --git a/library/core/src/num/f16.rs b/library/core/src/num/f16.rs
@@ -880,13 +880,13 @@ impl f16 {
             // Overflow is impossible
             (a + b) / 2.
         } else if abs_a < LO {
-            // Not safe to halve a
+            // Not safe to halve `a` (would underflow)
             a + (b / 2.)
         } else if abs_b < LO {
-            // Not safe to halve b
+            // Not safe to halve `b` (would underflow)
             (a / 2.) + b
         } else {
-            // Not safe to halve a and b
+            // Safe to halve `a` and `b`
             (a / 2.) + (b / 2.)
         }
     }

diff --git a/library/core/src/num/f32.rs b/library/core/src/num/f32.rs
@@ -1070,13 +1070,13 @@ impl f32 {
                     // Overflow is impossible
                     (a + b) / 2.
                 } else if abs_a < LO {
-                    // Not safe to halve a
+                    // Not safe to halve `a` (would underflow)
                     a + (b / 2.)
                 } else if abs_b < LO {
-                    // Not safe to halve b
+                    // Not safe to halve `b` (would underflow)
                     (a / 2.) + b
                 } else {
-                    // Not safe to halve a and b
+                    // Safe to halve `a` and `b`
                     (a / 2.) + (b / 2.)
                 }
             }

diff --git a/library/core/src/num/f64.rs b/library/core/src/num/f64.rs
@@ -1064,13 +1064,13 @@ impl f64 {
             // Overflow is impossible
             (a + b) / 2.
         } else if abs_a < LO {
-            // Not safe to halve a
+            // Not safe to halve `a` (would underflow)
             a + (b / 2.)
         } else if abs_b < LO {
-            // Not safe to halve b
+            // Not safe to halve `b` (would underflow)
             (a / 2.) + b
         } else {
-            // Not safe to halve a and b
+            // Safe to halve `a` and `b`
             (a / 2.) + (b / 2.)
         }
     }