# isTotallyOrdered(belowOrEqualTo:) Returns a Boolean value indicating whether this instance should precede or tie positions with the given value in an ascending sort. ``` func isTotallyOrdered(belowOrEqualTo other: Self) -> Bool ``` ## Parameters `other` A floating-point value to compare to this value. ## Return Value `true` if this value is ordered below or the same as `other` in a total ordering of the floating-point type; otherwise, `false`. ## Discussion This relation is a refinement of the less-than-or-equal-to operator (`<=`) that provides a total order on all values of the type, including signed zeros and NaNs. The following example uses `isTotallyOrdered(belowOrEqualTo:)` to sort an array of floating-point values, including some that are NaN: ``` var numbers = [2.5, 21.25, 3.0, .nan, -9.5] numbers.sort { !$1.isTotallyOrdered(belowOrEqualTo: $0) } print(numbers) // Prints "[-9.5, 2.5, 3.0, 21.25, nan]" ``` The `isTotallyOrdered(belowOrEqualTo:)` method implements the total order relation as defined by the [IEEE 754 specification](http://ieeexplore.ieee.org/servlet/opac?punumber=4610933). --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)