Double.NaN Field

Reference

Definition

Namespace:: System

Assembly:: System.Runtime.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Source:: Double.cs

Source:: Double.cs

Source:: Double.cs

Important

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Represents a value that is not a number (NaN). This field is constant.

public: double NaN = NaN;

public const double NaN = NaN;

val mutable NaN : double

Public Const NaN As Double  = NaN

Field Value

Value = NaN

Double

Examples

The following example illustrates the use of NaN.

Double zero = 0;

// This condition will return false.
if ( (0 / zero) == Double::NaN )
{
   Console::WriteLine( "0 / 0 can be tested with Double::NaN." );
}
else
{
   Console::WriteLine( "0 / 0 cannot be tested with Double::NaN; use Double::IsNan() instead." );
}

Double zero = 0;
  
// This condition will return false.
if ((0 / zero) == Double.NaN)
   Console.WriteLine("0 / 0 can be tested with Double.NaN.");
else
   Console.WriteLine("0 / 0 cannot be tested with Double.NaN; use Double.IsNan() instead.");

let zero = 0.

// This condition will return false.
if 0. / zero = Double.NaN then
    printfn "0 / 0 can be tested with Double.NaN."
else
    printfn "0 / 0 cannot be tested with Double.NaN use Double.IsNan() instead."

Dim zero As Double = 0

' This condition will return false.
If (0 / zero) = Double.NaN Then
    Console.WriteLine("0 / 0 can be tested with Double.NaN.")
Else
    Console.WriteLine("0 / 0 cannot be tested with Double.NaN; use Double.IsNan() instead.")
End If

Remarks

A method or operator returns NaN when the result of an operation is undefined. For example, the result of dividing zero by zero is NaN, as the following example shows. (However, dividing a non-zero number by zero returns either PositiveInfinity or NegativeInfinity, depending on the sign of the divisor.)

double zero = 0.0;
Console.WriteLine("{0} / {1} = {2}", zero, zero, zero/zero);
// The example displays the following output:
//         0 / 0 = NaN

let zero = 0.0
printfn $"{zero} / {zero} = {zero / zero}"
// The example displays the following output:
//         0 / 0 = NaN

Dim zero As Double = 0
Console.WriteLine("{0} / {1} = {2}", zero, zero, zero/zero)
' The example displays the following output:
'         0 / 0 = NaN

In addition, a method call with a NaN value or an operation on a NaN value returns NaN, as the following example shows.

double nan1 = Double.NaN;

Console.WriteLine("{0} + {1} = {2}", 3, nan1, 3 + nan1);
Console.WriteLine("Abs({0}) = {1}", nan1, Math.Abs(nan1));
// The example displays the following output:
//       3 + NaN = NaN
//       Abs(NaN) = NaN

let nan1 = Double.NaN

printfn $"{3} + {nan1} = {3. + nan1}"
printfn $"abs({nan1}) = {abs nan1}"
// The example displays the following output:
//       3 + NaN = NaN
//       abs NaN = NaN

Dim nan1 As Double = Double.NaN

Console.WriteLine("{0} + {1} = {2}", 3, nan1, 3 + nan1)
Console.WriteLine("Abs({0}) = {1}", nan1, Math.Abs(nan1))
' The example displays the following output:
'       3 + NaN = NaN
'       Abs(NaN) = NaN

Use the IsNaN method to determine whether a value is not a number. The Equality operator considers two NaN values to be unequal to one another. In general, Double operators cannot be used to compare Double.NaN with other Double values, although comparison methods (such as Equals and CompareTo) can. The following example illustrates the difference in behavior between Double comparison operators and methods.

using System;

public class Example
{
   public static void Main()
   {
      Console.WriteLine("NaN == NaN: {0}", Double.NaN == Double.NaN);
      Console.WriteLine("NaN != NaN: {0}", Double.NaN != Double.NaN);
      Console.WriteLine("NaN.Equals(NaN): {0}", Double.NaN.Equals(Double.NaN));
      Console.WriteLine("! NaN.Equals(NaN): {0}", ! Double.NaN.Equals(Double.NaN));
      Console.WriteLine("IsNaN: {0}", Double.IsNaN(Double.NaN));

      Console.WriteLine("\nNaN > NaN: {0}", Double.NaN > Double.NaN);
      Console.WriteLine("NaN >= NaN: {0}", Double.NaN >= Double.NaN);
      Console.WriteLine("NaN < NaN: {0}", Double.NaN < Double.NaN);
      Console.WriteLine("NaN < 100.0: {0}", Double.NaN < 100.0);
      Console.WriteLine("NaN <= 100.0: {0}", Double.NaN <= 100.0);
      Console.WriteLine("NaN >= 100.0: {0}", Double.NaN > 100.0);
      Console.WriteLine("NaN.CompareTo(NaN): {0}", Double.NaN.CompareTo(Double.NaN));
      Console.WriteLine("NaN.CompareTo(100.0): {0}", Double.NaN.CompareTo(100.0));
      Console.WriteLine("(100.0).CompareTo(Double.NaN): {0}", (100.0).CompareTo(Double.NaN));
   }
}
// The example displays the following output:
//       NaN == NaN: False
//       NaN != NaN: True
//       NaN.Equals(NaN): True
//       ! NaN.Equals(NaN): False
//       IsNaN: True
//
//       NaN > NaN: False
//       NaN >= NaN: False
//       NaN < NaN: False
//       NaN < 100.0: False
//       NaN <= 100.0: False
//       NaN >= 100.0: False
//       NaN.CompareTo(NaN): 0
//       NaN.CompareTo(100.0): -1
//       (100.0).CompareTo(Double.NaN): 1

open System

printfn $"NaN = NaN: {Double.NaN = Double.NaN}"
printfn $"NaN <> NaN: {Double.NaN <> Double.NaN}"
printfn $"NaN.Equals(NaN): {Double.NaN.Equals Double.NaN}"
printfn $"not (NaN.Equals NaN): {not (Double.NaN.Equals Double.NaN)}"
printfn $"IsNaN: {Double.IsNaN Double.NaN}"

printfn $"\nNaN > NaN: {Double.NaN > Double.NaN}"
printfn $"NaN >= NaN: {Double.NaN >= Double.NaN}"
printfn $"NaN < NaN: {Double.NaN < Double.NaN}"
printfn $"NaN < 100.0: {Double.NaN < 100.0}"
printfn $"NaN <= 100.0: {Double.NaN <= 100.0}"
printfn $"NaN >= 100.0: {Double.NaN > 100.0}"
printfn $"NaN.CompareTo(NaN): {Double.NaN.CompareTo Double.NaN}"
printfn $"NaN.CompareTo(100.0): {Double.NaN.CompareTo 100.0}"
printfn $"(100.0).CompareTo(Double.NaN): {(100.0).CompareTo Double.NaN}"
// The example displays the following output:
//       NaN = NaN: False
//       NaN <> NaN: True
//       NaN.Equals(NaN): True
//       not (NaN.Equals NaN): False
//       IsNaN: True
//
//       NaN > NaN: False
//       NaN >= NaN: False
//       NaN < NaN: False
//       NaN < 100.0: False
//       NaN <= 100.0: False
//       NaN >= 100.0: False
//       NaN.CompareTo(NaN): 0
//       NaN.CompareTo(100.0): -1
//       (100.0).CompareTo(Double.NaN): 1

Module Example
   Public Sub Main()
      Console.WriteLine("NaN = NaN: {0}", Double.NaN = Double.NaN) 
      Console.WriteLine("NaN <> NaN: {0}", Double.NaN <> Double.NaN) 
      Console.WriteLine("NaN.Equals(NaN): {0}", Double.NaN.Equals(Double.NaN)) 
      Console.WriteLine("Not NaN.Equals(NaN): {0}", Not Double.NaN.Equals(Double.NaN)) 
      Console.WriteLine("IsNaN: {0}", Double.IsNaN(Double.NaN))
      Console.WriteLine()
      Console.WriteLine("NaN > NaN: {0}", Double.NaN > 100.0) 
      Console.WriteLine("NaN >= NaN: {0}", Double.NaN >= 100.0) 
      Console.WriteLine("NaN < NaN: {0}", Double.NaN < Double.NaN)
      Console.WriteLine("NaN < 100.0: {0}", Double.NaN < 100.0) 
      Console.WriteLine("NaN <= 100.0: {0}", Double.NaN <= 100.0) 
      Console.WriteLine("NaN >= 100.0: {0}", Double.NaN > 100.0)
      Console.WriteLine("NaN.CompareTo(NaN): {0}", Double.NaN.CompareTo(Double.Nan)) 
      Console.WriteLine("NaN.CompareTo(100.0): {0}", Double.NaN.CompareTo(100.0)) 
      Console.WriteLine("(100.0).CompareTo(Double.NaN): {0}", (100.0).CompareTo(Double.NaN)) 
   End Sub
End Module
' The example displays the following output:
'       NaN == NaN: False
'       NaN != NaN: True
'       NaN.Equals(NaN): True
'       ! NaN.Equals(NaN): False
'       IsNaN: True
'
'       NaN > NaN: False
'       NaN >= NaN: False
'       NaN < NaN: False
'       NaN < 100.0: False
'       NaN <= 100.0: False
'       NaN >= 100.0: False
'       NaN.CompareTo(NaN): 0
'       NaN.CompareTo(100.0): -1
'       (100.0).CompareTo(Double.NaN): 1

Applies to

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