Some return values for MathF.Pow() are wrong

[Psychpsyo]

Summary

MathF.Pow(float.NaN,0f) returns 1, not NaN.
MathF.Pow(1f,float.NaN) returns 1, not NaN.

using System;

public class HelloWorld
{
    public static void Main(string[] args)
    {
        Console.WriteLine(System.MathF.Pow(float.NaN,0f));
        Console.WriteLine(System.MathF.Pow(1f,float.NaN));
    }
}

This outputs 1 twice.

[learn-build-service-prod]

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[tannergooding]

The full set of rules for pow (as required by IEEE 754 2019) is:

• pow (x, ±0) is 1 if x is not a signaling NaN
• pow (±0, y) is ±∞ and signals the divideByZero exception for y an odd integer < 0
• pow (±0, −∞) is +∞ with no exception
• pow (±0, +∞) is +0 with no exception
• pow (±0, y) is ±0 for finite y > 0 an odd integer
• pow (−1, ±∞) is 1 with no exception
• pow (+1, y) is 1 for any y (even a quiet NaN)
• pow (x, +∞) is +0 for −1 < x < 1
• pow (x, +∞) is +∞ for x < −1 or for 1 < x (including ±∞)
• pow (x, −∞) is +∞ for −1 < x < 1
• pow (x, −∞) is +0 for x < −1 or for 1 < x (including ±∞)
• pow (+∞, y) is +0 for a number y < 0
• pow (+∞, y) is +∞ for a number y > 0
• pow (−∞, y) is −0 for finite y < 0 an odd integer
• pow (−∞, y) is −∞ for finite y > 0 an odd integer
• pow (−∞, y) is +0 for finite y < 0 and not an odd integer
• pow (−∞, y) is +∞ for finite y > 0 and not an odd integer
• pow (±0, y) is +∞ and signals the divideByZero exception for finite y < 0 and not an odd integer
• pow(±0, y) is +0 for finite y > 0 and not an odd integer
• pow(x, y) signals the invalid operation exception for finite x < 0 and finite non-integer y.

It would be good to see if we can make all of this match up with the docs

[Psychpsyo]

It would be good to see if we can make all of this match up with the docs

Except for the parts about signaling NaNs, I'd say, since I don't think we even have access to signaling NaNs.

[learn-build-service-prod]

Learn Build status updates of commit 4ebb77c:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/System/MathF.xml	✅Succeeded	View

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel