Documentation for method isNaN assembled from the following types:

role Rational

From Rational

(Rational) method isNaN

method isNaN(Rational:D: --> Bool:D)

Tests whether the invocant's Num value is a NaN, an acronym for Not available Number. That is both its numerator and denominator are zero.

class Complex

From Complex

(Complex) method isNaN

Defined as:

method isNaN(Complex:D: --> Bool:D)

Returns true if the real or imaginary part is NaN (not a number).

say (NaN+5i).isNaN; # OUTPUT: «True␤» 
say (7+5i).isNaN;   # OUTPUT: «False␤»