What the NaN?
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var result = new[] { 1, double.PositiveInfinity, double.NegativeInfinity, double.NaN }.Max(); // Infinity
var result = new[] { 1, double.PositiveInfinity, double.NegativeInfinity, double.NaN }.Min(); // NaN
var isNaNSmaller = double.NaN < 1; // falseSo NaN is not the biggest value, it's still bigger than one, but it's also the smallest value. I hate to sound infinitely negative, but that's messed up :wtf:
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
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var result = new[] { 1, double.PositiveInfinity, double.NegativeInfinity, double.NaN }.Max(); // Infinity
var result = new[] { 1, double.PositiveInfinity, double.NegativeInfinity, double.NaN }.Min(); // NaN
var isNaNSmaller = double.NaN < 1; // falseSo NaN is not the biggest value, it's still bigger than one, but it's also the smallest value. I hate to sound infinitely negative, but that's messed up :wtf:
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
Here's the reasoning from the source code[^]:
// Normally NaN < anything is false, as is anything < NaN // However, this leads to some irksome outcomes in Min and Max. // If we use those semantics then Min(NaN, 5.0) is NaN, but // Min(5.0, NaN) is 5.0! To fix this, we impose a total // ordering where NaN is smaller than every value, including // negative infinity.GeoGame for Windows Phone | The Lounge Explained In 5 Minutes
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I would recommend you to this article before you continue your rant about IEEE754.
GeoGame for Windows Phone | The Lounge Explained In 5 Minutes
Tried to read it once, but to me it makes as much sense as the whole NaN implementation: none whatsoever (and I admit my limited math skills are to blame). However, I tried reading the NaN part and what they basically say is that in some edge cases you don't want computations to stop (throw exceptions) when some bogus values are inserted (e.g. divide by 0). The workaround without NaN would be to catch exceptions and simply try again. Unfortunately, every language handles exceptions differently so they standardized on NaN. Awesome, they destroyed our numeric system to support some edge cases (correct me if I'm wrong) :D Luckily .NET offers some sensible numeric types with int, long and decimal :D Unfortunately, I'm currently working in JavaScript, with floating point arithmetic, where NaN is quite common, and 0.1 + 0.2 equals 0.30000000000000004 (yes, I know that's IEEE754, but that doesn't make it right) :sigh:
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
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Here's the reasoning from the source code[^]:
// Normally NaN < anything is false, as is anything < NaN // However, this leads to some irksome outcomes in Min and Max. // If we use those semantics then Min(NaN, 5.0) is NaN, but // Min(5.0, NaN) is 5.0! To fix this, we impose a total // ordering where NaN is smaller than every value, including // negative infinity.GeoGame for Windows Phone | The Lounge Explained In 5 Minutes
Thanks, good find! At least that clears that up! :D
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
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Here's the reasoning from the source code[^]:
// Normally NaN < anything is false, as is anything < NaN // However, this leads to some irksome outcomes in Min and Max. // If we use those semantics then Min(NaN, 5.0) is NaN, but // Min(5.0, NaN) is 5.0! To fix this, we impose a total // ordering where NaN is smaller than every value, including // negative infinity.GeoGame for Windows Phone | The Lounge Explained In 5 Minutes
By the way, the email for this message had a YouTube link attached to it. I just found it in your sig :laugh: And I would once again argue that the existence of NaN is just plain wrong. Well, at least you're right about the Lounge ;p
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
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BillWoodruff wrote:
that implies the treatment of double.NaN in the 'Min function is different than in the 'Max function.
I doubt it there is different treatment, it's just different implementation of if condition. For instance, Min method could have this condition:
if (currentMin > values[i])
currentMin = values[i];and Max this one:
if (!(currentMax > values[i]))
currentMax = values[i];If Max was implemented in this way:
if (currentMax < values[i])
currentMax = values[i];it would return
NaNalso. edit: I'll be damned. NaN indeed has different treatment in Min method. Comment from the source code[^]:// Normally NaN < anything is false, as is anything < NaN
// However, this leads to some irksome outcomes in Min and Max.
// If we use those semantics then Min(NaN, 5.0) is NaN, but
// Min(5.0, NaN) is 5.0! To fix this, we impose a total
// ordering where NaN is smaller than every value, including
// negative infinity.
if (x < value || System.Single.IsNaN(x)) value = x;GeoGame for Windows Phone | The Lounge Explained In 5 Minutes
Mladen Janković wrote:
I'll be damned. NaN indeed has different treatment
Oh my, are you saying that my post actually meant something ? If that's the case, I hereby offer you enough plenary indulgence to be un-damned ... once you have voted.
«There is a spectrum, from "clearly desirable behaviour," to "possibly dodgy behavior that still makes some sense," to "clearly undesirable behavior." We try to make the latter into warnings or, better, errors. But stuff that is in the middle category you don’t want to restrict unless there is a clear way to work around it.» Eric Lippert, May 14, 2008
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Richard MacCutchan wrote:
So you cannot equate it to any numeric value
Yes you can, and that's the point. I expected either an exception (compile or run time) or at least a predictable weird behavior (well, it's predictable once you know all the edge cases I guess). Now whether you should is a different discussion... :) I found this because I had some weird JavaScript bug by the way, casting some object to a number results in NaN and I was wondering how C# handled the case the followed. NaN is not smaller than 1 (when comparing and when using the Min function), but when both are thrown into the Max function NaN is smaller than 1. Got it :~ Luckily, I've never had to work with NaN in C# because why would there even be a NaN anyway...
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
To my mind, the only reasonable operations with NaN are assigning an lvalue to NaN and comparing a value to NaN for equality and inequality. Any of the arithmetic operators ought to yield NaN (or throw an exception). Come to think of it, the IEEE must have a formal document that describes all of this behavior. Pardon me while I JFGI... Ahh; typical. The formal document is only available to IEEE members who know the official circle jerk handshake. NaN - Wikipedia, the free encyclopedia[^] is a quick article that describes background and informally NaN's usage. This article: IEEE Standard 754 Floating-Point[^] also has some discussion on NaN behavior.
Software Zen:
delete this; -
var result = new[] { 1, double.PositiveInfinity, double.NegativeInfinity, double.NaN }.Max(); // Infinity
var result = new[] { 1, double.PositiveInfinity, double.NegativeInfinity, double.NaN }.Min(); // NaN
var isNaNSmaller = double.NaN < 1; // falseSo NaN is not the biggest value, it's still bigger than one, but it's also the smallest value. I hate to sound infinitely negative, but that's messed up :wtf:
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
Did you know that both
1 < double.NaNand1 > double.NaNare false?! ;PA new .NET Serializer All in one Menu-Ribbon Bar Taking over the world since 1371!
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So it's completely dependent on the internals of Min and Max. Had Max checked if any values were smaller than the current then NaN would always be max and had Min checked if any values were greater than the current then NaN would never be min. So change your implementation and NaN will behave differently, feels very random.
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
Sander Rossel wrote:
NaN will behave differently, feels very random.
Sander, this is a brilliant idea you've come up with; I'll offer a quick sketch, and look forward to your comprehensive implementation:
namespace CatState
{
public static class CatStateExtensions
{
public static double CatDead(this double[] args)
{
if (args.Contains(double.NaN))
{
Random rnd = new Random((int) DateTime.Now.Ticks);return (rnd.Next(0,2) == 0) ? double.PositiveInfinity : double.NegativeInfinity; } return args.Min(); } public static double CatAlive(this double\[\] args) { if (args.Contains(double.NaN)) { Random rnd = new Random((int) DateTime.Now.Ticks); return (rnd.Next(0,2) == 1) ? double.PositiveInfinity : double.NegativeInfinity; } return args.Max(); } }}
The half-dead cats fighting over half-dead fish-heads have been keeping me up nights, lately.
«There is a spectrum, from "clearly desirable behaviour," to "possibly dodgy behavior that still makes some sense," to "clearly undesirable behavior." We try to make the latter into warnings or, better, errors. But stuff that is in the middle category you don’t want to restrict unless there is a clear way to work around it.» Eric Lippert, May 14, 2008
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Tried to read it once, but to me it makes as much sense as the whole NaN implementation: none whatsoever (and I admit my limited math skills are to blame). However, I tried reading the NaN part and what they basically say is that in some edge cases you don't want computations to stop (throw exceptions) when some bogus values are inserted (e.g. divide by 0). The workaround without NaN would be to catch exceptions and simply try again. Unfortunately, every language handles exceptions differently so they standardized on NaN. Awesome, they destroyed our numeric system to support some edge cases (correct me if I'm wrong) :D Luckily .NET offers some sensible numeric types with int, long and decimal :D Unfortunately, I'm currently working in JavaScript, with floating point arithmetic, where NaN is quite common, and 0.1 + 0.2 equals 0.30000000000000004 (yes, I know that's IEEE754, but that doesn't make it right) :sigh:
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
Sander Rossel wrote:
they destroyed our numeric system to support some edge cases
Any representation of real numbers in computer memory will destroy 'numeric system' since you're trying to represent infinite set with finite amount of memory.
Sander Rossel wrote:
Luckily .NET offers some sensible numeric types with int, long and decimal :-D
decimalcomes with performance costs as it has no support in hardware so it might not be suitable as a replacement in fields that traditionally use floating point arithmetic. It is meant to be used for financial stuff since IEEE754 is not suitable for that purpose, so not everyone have to invent their own way of doing math.Sander Rossel wrote:
0.1 + 0.2 equals 0.30000000000000004
That's the problem with converting real numbers between different bases.
GeoGame for Windows Phone | The Lounge Explained In 5 Minutes
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Sander Rossel wrote:
NaN will behave differently, feels very random.
Sander, this is a brilliant idea you've come up with; I'll offer a quick sketch, and look forward to your comprehensive implementation:
namespace CatState
{
public static class CatStateExtensions
{
public static double CatDead(this double[] args)
{
if (args.Contains(double.NaN))
{
Random rnd = new Random((int) DateTime.Now.Ticks);return (rnd.Next(0,2) == 0) ? double.PositiveInfinity : double.NegativeInfinity; } return args.Min(); } public static double CatAlive(this double\[\] args) { if (args.Contains(double.NaN)) { Random rnd = new Random((int) DateTime.Now.Ticks); return (rnd.Next(0,2) == 1) ? double.PositiveInfinity : double.NegativeInfinity; } return args.Max(); } }}
The half-dead cats fighting over half-dead fish-heads have been keeping me up nights, lately.
«There is a spectrum, from "clearly desirable behaviour," to "possibly dodgy behavior that still makes some sense," to "clearly undesirable behavior." We try to make the latter into warnings or, better, errors. But stuff that is in the middle category you don’t want to restrict unless there is a clear way to work around it.» Eric Lippert, May 14, 2008
BillWoodruff wrote:
Random rnd = new Random((int) DateTime.Now.Ticks);
Reseeding RNG each time you make a call with nothing more than current time as a source of randomness, that's just a disaster waiting to happen. Output of your methods would be easily predictable. Nobody want their Schrödinger's cat predictable :)
GeoGame for Windows Phone | The Lounge Explained In 5 Minutes
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So it's completely dependent on the internals of Min and Max. Had Max checked if any values were smaller than the current then NaN would always be max and had Min checked if any values were greater than the current then NaN would never be min. So change your implementation and NaN will behave differently, feels very random.
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
The behaviour of comparing with Nan is defined. The implementation of Min and Max is probably not. But a Min function is usually implemented as x < y ? x : y instead of !(x >= y) ? x : y Overall, comparing with NaN makes no sense as already noted by others. Just change the order of your elements (e.g. NaN as first element).
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BillWoodruff wrote:
Random rnd = new Random((int) DateTime.Now.Ticks);
Reseeding RNG each time you make a call with nothing more than current time as a source of randomness, that's just a disaster waiting to happen. Output of your methods would be easily predictable. Nobody want their Schrödinger's cat predictable :)
GeoGame for Windows Phone | The Lounge Explained In 5 Minutes
Hi Mladen, DateTime.Now.Ticks "is the number of 100-nanosecond intervals that have elapsed since 1/1/0001, 12:00am." Yes: if you had a loop calling that function faster than 100 ns., you could get a duplicate seed, and what you suggest is better practice. If "heavier-duty randomness" were required I would use the Crypto library. In real-world code, I would create a single static instance of 'Random, and re-use it. I wrote that code while I was half-dead, although that's a very poor excuse :) cheers, Bill
«There is a spectrum, from "clearly desirable behaviour," to "possibly dodgy behavior that still makes some sense," to "clearly undesirable behavior." We try to make the latter into warnings or, better, errors. But stuff that is in the middle category you don’t want to restrict unless there is a clear way to work around it.» Eric Lippert, May 14, 2008
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Did you know that both
1 < double.NaNand1 > double.NaNare false?! ;PA new .NET Serializer All in one Menu-Ribbon Bar Taking over the world since 1371!
I thought Julian Assange had called off his latest announcement of new WikiLeak content: [^]. Revelations like this, calling into question the entire structure of the way we view reality and the code tools we use to model it, is going to really shake things up. The thought of the vast infinite hordes that NaN could mobilize and unleash on Primes and NotPrimes and SubPrimes ... frightening. I'm going to start building my bunker, now.
«There is a spectrum, from "clearly desirable behaviour," to "possibly dodgy behavior that still makes some sense," to "clearly undesirable behavior." We try to make the latter into warnings or, better, errors. But stuff that is in the middle category you don’t want to restrict unless there is a clear way to work around it.» Eric Lippert, May 14, 2008
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I thought Julian Assange had called off his latest announcement of new WikiLeak content: [^]. Revelations like this, calling into question the entire structure of the way we view reality and the code tools we use to model it, is going to really shake things up. The thought of the vast infinite hordes that NaN could mobilize and unleash on Primes and NotPrimes and SubPrimes ... frightening. I'm going to start building my bunker, now.
«There is a spectrum, from "clearly desirable behaviour," to "possibly dodgy behavior that still makes some sense," to "clearly undesirable behavior." We try to make the latter into warnings or, better, errors. But stuff that is in the middle category you don’t want to restrict unless there is a clear way to work around it.» Eric Lippert, May 14, 2008
Doom is upon us! Or will be anytime soon now! :omg:
A new .NET Serializer All in one Menu-Ribbon Bar Taking over the world since 1371!
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I'm glad that a lot of people have thought about how NaN should have contradictory results in different usages :doh: <Edit> So it seems the contradictory result are in IEEE 754, but the weird behavior in Min and Max is Microsoft[^] :laugh: </Edit>
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
That is true. But keep in mind that the Min and Max functions have nothing to do with C# - they are written in C#; yes, but they are part of the LINQ / the .NET Framework. The difference in both is that Max excludes NaN, while Min will take NaN exclusively. You can see the difference here (Min)[^] and here (Max)[^]. That is different to some JS functions (such as everything in Math), which are defined by the same specification as the language.
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Hi Mladen, DateTime.Now.Ticks "is the number of 100-nanosecond intervals that have elapsed since 1/1/0001, 12:00am." Yes: if you had a loop calling that function faster than 100 ns., you could get a duplicate seed, and what you suggest is better practice. If "heavier-duty randomness" were required I would use the Crypto library. In real-world code, I would create a single static instance of 'Random, and re-use it. I wrote that code while I was half-dead, although that's a very poor excuse :) cheers, Bill
«There is a spectrum, from "clearly desirable behaviour," to "possibly dodgy behavior that still makes some sense," to "clearly undesirable behavior." We try to make the latter into warnings or, better, errors. But stuff that is in the middle category you don’t want to restrict unless there is a clear way to work around it.» Eric Lippert, May 14, 2008
BillWoodruff wrote:
I wrote that code while I was half-dead, although that's a very poor excuse :)
Not if you're actually Schrödinger's Bill! :omg:
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
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The behaviour of comparing with Nan is defined. The implementation of Min and Max is probably not. But a Min function is usually implemented as x < y ? x : y instead of !(x >= y) ? x : y Overall, comparing with NaN makes no sense as already noted by others. Just change the order of your elements (e.g. NaN as first element).
Jochen Arndt wrote:
The implementation of Min and Max is probably not. But a Min function is usually implemented as x < y ? x : y instead of !(x >= y) ? x : y
Actually Min and Max don't treat NaN as they should to get predictable results, as pointed out by Mladen :D
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
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Did you know that both
1 < double.NaNand1 > double.NaNare false?! ;PA new .NET Serializer All in one Menu-Ribbon Bar Taking over the world since 1371!
I know, which makes its behavior in Min and Max even more random :D Although, as it turns out, it's not random at all. Min and Max just treat NaN as lower than anything else.
Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.
Simplicity is prerequisite for reliability. — Edsger W. Dijkstra
Regards, Sander
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NaN means Not a Number, so you cannot compare it to a proper number and get a valid response.
And with that the case is more than closed. :thumbsup:
GCS d--- s-/++ a- C++++ U+++ P- L- E-- W++ N++ o+ K- w+++ O? M-- V? PS+ PE- Y+ PGP t++ 5? X R++ tv-- b+ DI+++ D++ G e++>+++ h--- ++>+++ y+++* Weapons extension: ma- k++ F+2 X If you think 'goto' is evil, try writing an Assembly program without JMP. -- TNCaver When I was six, there were no ones and zeroes - only zeroes. And not all of them worked. -- Ravi Bhavnani
