MATLAB Function Reference

NaN

Not-a-Number

Syntax

• NaN
  

Description

NaN returns the IEEE arithmetic representation for Not-a-Number (NaN). These result from operations which have undefined numerical results.

Examples

These operations produce NaN:

• Any arithmetic operation on a NaN, such as sqrt(NaN)
• Addition or subtraction, such as magnitude subtraction of infinities as (+Inf)+(-Inf)
• Multiplication, such as 0*Inf
• Division, such as 0/0 and Inf/Inf
• Remainder, such as rem(x,y) where y is zero or x is infinity

Remarks

Because two NaNs are not equal to each other, logical operations involving NaNs always return false, except ~= (not equal). Consequently,

• NaN ~= NaN 
  ans =
       1
  NaN == NaN
  ans =
       0
  

and the NaNs in a vector are treated as different unique elements.

• unique([1 1 NaN NaN])
  ans = 
       1 NaN NaN
  

Use the isnan function to detect NaNs in an array.

• isnan([1 1 NaN NaN])
  ans =
       0     0     1     1
  

See Also

Inf, isnan

namelengthmax

nargchk