| Description |  
The NaN constant provides a standard undetrmined number value for assigning to floating point variables.
   
It allows the floating point number to be treated as unassigned.
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| Related commands |  
| Infinity | 
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Floating point value of infinite size | 
 
| IsInfinite | 
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Checks whether a floating point number is infinite | 
 
| IsNaN | 
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Checks to see if a floating point number holds a real number | 
 
 
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| Example code : Assign NAN to a number and then test using IsNaN |  
 var 
  float : Double; 
 
begin   // Set the number to an invalid number   float := NaN;     // Equivalent to 0.0/0.0 
   // Although an invalid number, we can still display it 
  ShowMessage('float = '+FloatToStr(float)); 
   // And we can test to see if it is a valid number 
  if IsNaN(float) 
  then ShowMessage('float is not a number') 
  else ShowMessage('float = '+FloatToStr(float)); 
end; 
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| Show full unit code | 
 
   float = NAN   
float is not a number 
 
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