function value = r8_is_nan ( r )

%*****************************************************************************80
%
%% R8_IS_NAN determines if an R8 represents a NaN value.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    14 May 2016
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    real R, the number to be checked.
%
%  Output:
%
%    integer VALUE, is true if R is a NaN
%
  value = ( r ~= r );

  return
end
