From c11a8e95b56626ab5b29d92b201688db26afdc8d Mon Sep 17 00:00:00 2001
From: Jochem <29899660+JochCool@users.noreply.github.com>
Date: Wed, 28 Dec 2022 19:30:00 +0100
Subject: [PATCH 1/2] Clarify INumber.IsPositive and INumber.IsNegative
 documentation

---
 .../src/System/Numerics/INumberBase.cs                    | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/libraries/System.Private.CoreLib/src/System/Numerics/INumberBase.cs b/src/libraries/System.Private.CoreLib/src/System/Numerics/INumberBase.cs
index 90f1d2db84006..92f8282a03115 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Numerics/INumberBase.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Numerics/INumberBase.cs
@@ -166,9 +166,9 @@ static virtual TSelf CreateTruncating<TOther>(TOther value)
         /// <returns><c>true</c> if <paramref name="value" /> is NaN; otherwise, <c>false</c>.</returns>
         static abstract bool IsNaN(TSelf value);
 
-        /// <summary>Determines if a value is negative.</summary>
+        /// <summary>Determines if a value represents a negative real number.</summary>
         /// <param name="value">The value to be checked.</param>
-        /// <returns><c>true</c> if <paramref name="value" /> is negative; otherwise, <c>false</c>.</returns>
+        /// <returns><c>true</c> if <paramref name="value" /> represents a negative real number; otherwise, <c>false</c>.</returns>
         /// <remarks>This function returning <c>false</c> does not imply that <see cref="IsPositive(TSelf)" /> will return <c>true</c>. A complex number, <c>a + bi</c> for non-zero <c>b</c>, is not positive nor negative</remarks>
         static abstract bool IsNegative(TSelf value);
 
@@ -191,9 +191,9 @@ static virtual TSelf CreateTruncating<TOther>(TOther value)
         /// </remarks>
         static abstract bool IsOddInteger(TSelf value);
 
-        /// <summary>Determines if a value is positive.</summary>
+        /// <summary>Determines if a value represents zero or a positive real number.</summary>
         /// <param name="value">The value to be checked.</param>
-        /// <returns><c>true</c> if <paramref name="value" /> is positive; otherwise, <c>false</c>.</returns>
+        /// <returns><c>true</c> if <paramref name="value" /> represents zero or a positive real number; otherwise, <c>false</c>.</returns>
         /// <remarks>This function returning <c>false</c> does not imply that <see cref="IsNegative(TSelf)" /> will return <c>true</c>. A complex number, <c>a + bi</c> for non-zero <c>b</c>, is not positive nor negative</remarks>
         static abstract bool IsPositive(TSelf value);
 

From 30c0ecfc7b964c7785672a195d4566dc941123ab Mon Sep 17 00:00:00 2001
From: Jochem <29899660+JochCool@users.noreply.github.com>
Date: Wed, 28 Dec 2022 22:07:17 +0100
Subject: [PATCH 2/2] Add clarification for negative zero

---
 .../src/System/Numerics/INumberBase.cs             | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/libraries/System.Private.CoreLib/src/System/Numerics/INumberBase.cs b/src/libraries/System.Private.CoreLib/src/System/Numerics/INumberBase.cs
index 92f8282a03115..0040a887d171b 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Numerics/INumberBase.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Numerics/INumberBase.cs
@@ -168,8 +168,11 @@ static virtual TSelf CreateTruncating<TOther>(TOther value)
 
         /// <summary>Determines if a value represents a negative real number.</summary>
         /// <param name="value">The value to be checked.</param>
-        /// <returns><c>true</c> if <paramref name="value" /> represents a negative real number; otherwise, <c>false</c>.</returns>
-        /// <remarks>This function returning <c>false</c> does not imply that <see cref="IsPositive(TSelf)" /> will return <c>true</c>. A complex number, <c>a + bi</c> for non-zero <c>b</c>, is not positive nor negative</remarks>
+        /// <returns><c>true</c> if <paramref name="value" /> represents negative zero or a negative real number; otherwise, <c>false</c>.</returns>
+        /// <remarks>
+        ///     <para>If this type has signed zero, then <c>-0</c> is also considered negative.</para>
+        ///     <para>This function returning <c>false</c> does not imply that <see cref="IsPositive(TSelf)" /> will return <c>true</c>. A complex number, <c>a + bi</c> for non-zero <c>b</c>, is not positive nor negative</para>
+        /// </remarks>
         static abstract bool IsNegative(TSelf value);
 
         /// <summary>Determines if a value is negative infinity.</summary>
@@ -193,8 +196,11 @@ static virtual TSelf CreateTruncating<TOther>(TOther value)
 
         /// <summary>Determines if a value represents zero or a positive real number.</summary>
         /// <param name="value">The value to be checked.</param>
-        /// <returns><c>true</c> if <paramref name="value" /> represents zero or a positive real number; otherwise, <c>false</c>.</returns>
-        /// <remarks>This function returning <c>false</c> does not imply that <see cref="IsNegative(TSelf)" /> will return <c>true</c>. A complex number, <c>a + bi</c> for non-zero <c>b</c>, is not positive nor negative</remarks>
+        /// <returns><c>true</c> if <paramref name="value" /> represents (positive) zero or a positive real number; otherwise, <c>false</c>.</returns>
+        /// <remarks>
+        ///     <para>If this type has signed zero, then <c>-0</c> is not considered positive, but <c>+0</c> is.</para>
+        ///     <para>This function returning <c>false</c> does not imply that <see cref="IsNegative(TSelf)" /> will return <c>true</c>. A complex number, <c>a + bi</c> for non-zero <c>b</c>, is not positive nor negative</para>
+        /// </remarks>
         static abstract bool IsPositive(TSelf value);
 
         /// <summary>Determines if a value is positive infinity.</summary>