Why is Mathf.Approximately(Infinity, Infinity) returning false?

I'm running into an issue where this equivalent code

Code (csharp):

1.  
2. Mathf.Approximately(Mathf.Infinity, Mathf.Infinity)
3.  

is returning false.

If I'm not mistaken, this should be evaluated as true as the floats are equal
Is this a bug in the API?

 

No. Infinity is not a number.
Infinity = infinity is not something you can determinate. The only assumption you can have is Infinity is > than any number.

On the top of that, Mathf.Approximately is this:
https://docs.unity3d.com/ScriptReference/Mathf.Approximately.html

 

Math.Approximately effectively is just:

Code (csharp):

1. Abs(a - b) < Epsilon

Where epsilon is a tiny value (like 0.0001)

So what you're asking is:

Code (csharp):

1. Abs(inf - inf) < Epsilon

But what is (inf - inf)?

How can you subtract infinity from infinity?

In the IEEE 754 floating point standard (what is used in unity for floats), inf - inf = NaN. And NaN always compares false (even to itself... NaN != NaN)

 

I guess I always assumed that Mathf.Infinity was actually just returning float.MaxValue.
Apparently this is not the case.

Unity API:
public const float Infinity = float.PositiveInfinity;

C# System.Single:
public const float MaxValue = 3.402823E+38;
public const float PositiveInfinity = ∞; //Unknown value?


The "==" evaluation is working for this situation.

Code (csharp):

1.  
2. var val1= Mathf.Infinity;
3.  var val2= Mathf.Infinity;
4.  
5.   if (val1 ==val2)
6.    {
7.           //Is evaluating to true
8.     }
9.  

Is there some other way to reliably check for this?

 

"Overriding" getting the remaining distance of a NavMeshAgent due to the Unity API returning 0 when the path is still being calculated. So basically the remaining distance is invalid if the path calculation is still being performed.

Code (csharp):

1.  
2. private float GetRemainingDistance ()
3.     {
4.         if (agent.pathPending) {        
5.             return +Mathf.Infinity;
6.         } else {
7.             return agent.remainingDistance;
8.         }
9.     }
10.  
11. if (GetRemainingDistance() == Mathf.Infinity)
12. {
13. //...
14. }
15.