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.

NaN('double') is the same as NaN with no inputs.

NaN('single') is the single precision representation of NaN.

NaN(n) is an n-by-n matrix of NaNs.

NaN(m,n) or NaN([m,n]) is an m-by-n matrix of NaNs.

NaN(m,n,p,...) or NaN([m,n,p,...]) is an m-by-n-by-p-by-... array of NaNs.

NaN(...,classname) is an array of NaNs of class specified by classname. classname must be either 'single' or 'double'.

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

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