[dmccarty]

Processors are inherently awesome at branching, adding, adding, shifting, etc. And shifting to get powers of 2 (i.e., KB vs. GB) is a superpower of its own. They're a little less awesome when it comes to math.pow(), math.log(), and math.log() / math.log().

Why 300K+ people copied this in the first place shows some basic level of ignorance about what's happening under the hood.[1]

As someone who's been at this for decades now and knows my own failings better than ever, it also shows how developers can be too attracted by shiny things (ooh look, you can solve it with logs instead, how clever!) at the expense of readable, maintainable code.

[1] But hey, maybe that's why we were all on StackOverflow in the first place

[JackFr]

> Processors are inherently awesome at branching, adding, adding, shifting, etc. And shifting to get powers of 2 (i.e., KB vs. GB) is a superpower of its own. They're a little less awesome when it comes to math.pow(), math.log(), and math.log() / math.log().

And here's something to consider -- if you're converting a number to human readable format it's more likely than not your about to do I/O with the resulting string, which is probably going to be an order of magnitude more expensive than the little function here.

[dmccarty]

Great point, I wish I'd mentioned it. The expense of the printf dwarfs the log / log (double divided by a double then cast to an int), which itself is greater than some repeated comparisons in a for loop.

It's key to be able to recognize this when thinking about performant code.

In other words, the entire exercise is silliness because the eventual printf is going to blow away any nanoseconds of savings by a smarter/shorter routine.

[sclangdon]

It's not that we think it's arcane or that we are in our own "bubbles of thought", it's that we aren't doing math. We're programming a computer. And a competent programmer would know, or at least suspect, that doing it with logarithms will be slower and more complicated for a computer. The author even points out that even he wouldn't use his solution.

P.S. Please look up the word literally.

[tasty_freeze]

> what are you people even programming that you need to know so absolutely little about how anything else in the entire world works

Feoren, your comment takes an incredibly superior attitude and accuses its reader, every reader, of being stupid.

When taking the log of a number, the value in general require an infinite number of digits to represent. Computing log(100) / log(10) should return 2.0 exactly, but since log(100) returns a fixed number of digits and log(10) returns a fixed number of digits, are you 100% confident that the ratio will be exactly 2.0?

Maybe you test it and it does return exactly 2.0 (to the degree floating point can be exactly any value). Are you confident that such a calculation will also work for any power of 10? Maybe they all work on this intel machine -- does it work on every Arm CPU? Every RISCV CPU? Etc. I wouldn't be, but if I wrote dumb "for" loop I'd be far more confident that I'd get the right result in every case.

[kalleboo]

> You're all literally writing CRUD React front-end javascript by copy-pasting "for" loops from StackOverflow?

To an approximation, yes.

The underlying calculations at my bank were probably written once in 1970 in COBOL and haven't changed meaningfully since. But the front-end UI to access it has gone from teletypes and punch cards to glass terminals to networked DOS to Win32 to ActiveX to Web 2.0 to React and mobile apps. Lots and lots of churn and work on the CRUD part, zero churn and work on the "need to remember logarithms" part.

AI? You have core teams building ChatGPT, Midjourney, etc. Then huge numbers of people accessing those via API, building CRUD sites to aggregate midjourney results and prompts, etc etc. Even Apple has made a drag-and-drop UI to train an AI object classifier, the ratio of people who had to know the math to make that vs the people using it is probably way above 1:100,000

Is this that surprising?

[prerok]

Well, maybe not exactly unmaintainable but I think most of us have learned that floating point operations are not to be trusted, especially if it needs to run on different processors. Furthermore, calling such math operations is an overkill most of the time. I would definitely never consider it for such a simple operation. I actually agree with you that it might look cleaner and easier to understand, but in my mind it would be such a heavy weight overkill I would never use it.