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Check whether symbolic array elements are NaNs




isnan(A) returns an array of the same size as A containing logical 1s (true) where the elements of A are symbolic NaNs, and logical 0s (false) where they are not.


Determine Which Elements of Symbolic Array Are NaNs

Using isnan, determine which elements of this symbolic matrix are NaNs:

isnan(sym([pi NaN Inf; 1 + i Inf + i NaN + i]))
ans =
  2×3 logical array
     0     1     0
     0     0     1

Input Arguments

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Input value, specified as a symbolic number, variable, expression, or function, or as an array, vector, or matrix of symbolic numbers, variables, expressions, functions.


  • For any A, exactly one of the three quantities isfinite(A), isinf(A), or isnan(A) is 1 for each element.

  • Symbolic expressions and functions containing NaN evaluate to NaN. For example, sym(NaN + i) returns symbolic NaN.

Version History

Introduced in R2013b