code: public static boolean isEquals(double x, double y, double eps) {
          return isEquals(x, y, 1) || Math.abs(y - x) <= eps;
      }
docs: Returns {@code true} if there is no double value strictly between the
  arguments or the difference between them is within the range of allowed
  error (inclusive).
  
  @param x   First value.
  @param y   Second value.
  @param eps Amount of allowed absolute error.
  @return {@code true} if the values are two adjacent floating point
  numbers or they are within range of each other.