isnan

Marks elements that are NaN (not a number).

Category: Language Fundamentals > Data Types

Syntax

tf = isnan(A)

Description

NaN is not equal to anything, itself included, so x == NaN is always false. The only reliable way to detect it is isnan.

Common uses are removing bad data, x(~isnan(x)), or counting it with sum(isnan(x)). Integer types have no NaN and give all false.

Input arguments

A

Numeric or logical array. A complex number is NaN if either part is NaN.

Output arguments

tf

Logical array the same size as A.

Example

Detecting and counting NaN

x = [4 NaN 7 NaN 1];
isnan(x)
x(~isnan(x))
sum(isnan(x))
NaN == NaN

ans = 1×5 logical array

   0   1   0   1   0
ans = 1×3

     4     7     1
ans = 2
ans = logical
   0

See also

isinf isfinite ismissing nan rmmissing