Function: isnan

isnan is a function defined in floatfns.c.

Signature

(isnan X)

Documentation

Return non-nil if argument X is a NaN.

Other relevant functions are documented in the number group.

View in manual

Probably introduced at or before Emacs version 24.1.

Shortdoc

;; number
(isnan 5.0)
    => nil

Source Code

// Defined in /usr/src/emacs/src/floatfns.c
{
  CHECK_FLOAT (x);
  return isnan (XFLOAT_DATA (x)) ? Qt : Qnil;
}