Sorry, but FTW will always mean "f... the world".
I've never seen it used that way. In WTF and FML, yes, but never in FTW.
In the dim and distant past it was used to mean that. See e.g. https://www.kayfabenews.com/study-majority-of-wrestling-fans...
14,000x Speedup (2015)
61–70 of 237 posts
Re: 14,000x Speedup (2015)
#62Earlier quoted context omitted.
People obsessed with big O are super annoying. To them O(1) trumps O(n) even if it's a tiny little set of data where clearly the latter is actually faster (stopwatch time).
It’s good to understand what the “Big O” for your algorithm is, but, yes, people who obsess over it are annoying. If I know I’m processing 100 items very rarely,[a] does it matter if my quick and dirty sorting (no pun intended) algorithm is bubble or quick sort? They both complete in a fraction of a second, and the user (generally) isn’t going to notice a difference between a single frame update delta or two. [a] Key…
My rule is that the only sort I will ever write by hand is a bubble sort. It's basically impossible to write incorrectly. If and when that breaks performance, then I will bring in an external sorting library and figure out what works the best for the data.
It's the equivalent philosophy to always buying the cheapest tool you can the first time around. When you break that tool, then you go out and buy the expensive one.
Re: 14,000x Speedup (2015)
#63Hacking through this and thinking himself so superior because he understands CS just makes the article feel pompous and self-aggrandizing. It's highlighting a personal win with notes about the shorter runtime being a team win.
CS is a wonderfully useful, deep and broad field. There's nothing so special about some simple Big O complexity that he couldn't have taught every developer in the department this rather than bragging and upstaging the person who wrote a correct but slow implementation. Patting all of CS on the proverbial back for this smells of gatekeeping.
Re: 14,000x Speedup (2015)
#64Earlier quoted context omitted.
Computer Science is just academic/theoretical programming. While having a relevant education usually beats not having one, real-world experience usually beats theoretical knowledge when it comes to achieving real-world gains. E.g. if I want something computed as quickly as possible I'm probably better off asking an average game engine programmer than an average CS professor, since they'll optimize for cache efficienc…
People obsessed with big O are super annoying. To them O(1) trumps O(n) even if it's a tiny little set of data where clearly the latter is actually faster (stopwatch time).
The way in which I like to often think about these things in practice is with "hidden" constant factors. For example, you can think of the O(1) algorithm as really taking O(1 * K1) time, and the O(n) algorithm taking O(n * K2) time to complete. For different algorithms, K1 and K2 will almost certainly be distinct, and may even differ by significant amounts. Of course, if K1 is less than K2, then the value of "n" is irrelevant, and the O(1) algorithm always completes faster. But if K1 is greater than K2, as is the case quite often, then this really depends on the nature of what "n" is in practice, and whether or not it is larger than the value of K1/K2. This of course still ignores any other, often important, considerations beyond just run time such as memory consumption (which may also affect run time indirectly), but I find it's a good starting point when trying to reason about when O(n) can run faster than O(1) in various real-world scenarios.
It's a good reminder to always try to understand your likely workloads as well as possible (know your "n"), and to get good measurements (what are K1 and K2 values) before prematurely optimizing these kinds of things.
Re: 14,000x Speedup (2015)
#65> In climate science we do a lot of downscaling. We take temperature and precipitation readings from a coarse scale Global Climate Model grid and map them to a fine scale local grid. Let’s say the global grid is 50x25 and the local grid is 1000x500. For each grid cell in the local grid, we want to know to which grid cell in the global grid it corresponds.
Climate scientist here. Colour me a little confused. We have a GCM which is (typically) on a structured grid, i.e. with latitudes & longitudes on a pixel-like grid. Finding the GCM (coarse) grid cell for a given latitude/longitude of the downscaled (fine) grid is an integer operation, i.e. invert lat = lat0 + i x delta_lat and lon = lon0 + j x delta_lon. Must be missing something here. Even if there is a strange projection, you can map it such that the deltas are uniform.
Re: 14,000x Speedup (2015)
#66Gamedev! One of the best parts of being in gamedev was that the problem space forces you to work this stuff out. People won’t wait 30 minutes for a frame to render. A few ways to solve this pop to mind. As Aeolun mentions in a parallel comment, you can just divide coordinates if your grid is regular. But it often isn’t. In that case, you can attack it in a few ways. One time Feynman was giving a lecture and said “Thi…
I've learned a few simple tricks about things like random numbers, rounding, simple physics (acceleration, inertia, gravity), etc just from following some tutorials in the pico-8 fantasy console.
And some people have taken that to extremes, building 3d rendering engines and tech demos in what is a very constrained environment.
Re: 14,000x Speedup (2015)
#67Earlier quoted context omitted.
> As a simple example, restricting amount of memory makes it possible to build a very simple algorithm to tell whether the program terminates or repeats ad infinitum, in finite time and resources. I feel like "finite" is doing a lot of work there.
At this point we are still talking mathematical terms. So, read it the following way: Mathematically, you can construct a program that, using finite amount of steps and finite amount of memory tells whether another program terminates or not IF you know this other program has finite amount of memory to use. Obviously, we know that even with very small amount of memory this is going to take huge amount of time. Just lo…
The busy beaver function assumes infinite memory, it is defined as a function of the number of states of the Turing machine (in a programming language this is program size). If it was memory then it would not be an undecidable sequence.
Re: 14,000x Speedup (2015)
#68Algorithms are important but are especially powerful in combination of knowing computer architecture and programming language intricacies. Many years ago I was asked to look at the program written in C++ that calculated Kendall-tau correlation matrix for a large amount of data. Basically Kendall Tau is a robust replacement for Pearson correlation and it had to be calculated for 0.5M^2 elements and calculation of each…
This is a usual problem with C++ and why I hate it. There's a lot going on under the hoods, and you must be really knowledgeable of the language to prevent stupid things. Following some idioms you can really avoid it, but it is useless since your coworkers will fall into the language traps.
I'd argue that not knowing the language you're working with is a problem that's not exclusive to C++.
There's so much more going on under the hood of more high level languages, that writing faster code is straight up black magic [1].
[1] https://stackoverflow.com/questions/28723658/python-why-is-i...
Re: 14,000x Speedup (2015)
#69Computer Science for the... loss? I did not study computer science in any substantial way, and I hardly consider myself a computer scientist, but I do have a nose for algorithms despite not really thinking about it in a structured way. I think lot of people get wrapped up in the notation without realizing they can approach the problem in a completely different way. Case in point, a professor at a University in the US…
There is nothing a computer science course teaches, or indeed, any university course really, that can't be learned by someone who didn't go through that course. Undergrad computer science is indeed one of the easiest things to self-teach because of the ready availability of the "lab materials", i.e., computers are cheap and abundant now. But a structured program will take you through these things, ensure that you und…
> that doesn't mean the structured experience is useless either
It also often seems missed that somebody who went through a formal degree in lieu of gaining real-world experience can also gain real-world experience at least as easily as somebody who got the equivalent of a formal degree through real-world experience.
Re: 14,000x Speedup (2015)
#70Gamedev! One of the best parts of being in gamedev was that the problem space forces you to work this stuff out. People won’t wait 30 minutes for a frame to render. A few ways to solve this pop to mind. As Aeolun mentions in a parallel comment, you can just divide coordinates if your grid is regular. But it often isn’t. In that case, you can attack it in a few ways. One time Feynman was giving a lecture and said “Thi…
Binary Space Partitioning tree.