I write code and play games and stuff. My old username from reddit and HN was already taken and I couldn’t think of anything else I wanted to be called so I just picked some random characters like this:

>>> import random
>>> ''.join([random.choice("abcdefghijklmnopqrstuvwxyz0123456789") for x in range(5)])
'e0qdk'

My avatar is a quick doodle made in KolourPaint. I might replace it later. Maybe.

日本語が少し分かるけど、下手です。

Alt: [email protected]

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  • 17 Comments
Joined 1 year ago
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Cake day: September 22nd, 2023

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  • It’s not a GUI library, but Jupyter was pretty much made for the kind of mathematical/scientific exploratory programming you’re interested in doing. It’s not the right tool for making finished products, but is intended for creating lab notebooks that contain executable code snippets, formatted text, and visual output together. Given your background experience and the libraries you like, it seems like it’d be right up your alley.


  • Can Z3 account for lost bits? Did it come up with just one solution?

    It gave me just one solution the way I asked for it. With additional constraints added to exclude the original solution, it also gives me a second solution – but the solution it produces is peculiar to my implementation and does not match your implementation. If you implemented exactly how the bits are supposed to end up in the result, you could probably find any other solutions that exist correctly, but I just did it in a quick and dirty way.

    This is (with a little clean up) what my code looked like:

    solver code
    #!/usr/bin/env python3
    
    import z3
    
    rand1 = 0.38203435111790895
    rand2 = 0.5012949781958014
    rand3 = 0.5278898433316499
    rand4 = 0.5114834443666041
    
    def xoshiro128ss(a,b,c,d):
        t = 0xFFFFFFFF & (b << 9)
        r = 0xFFFFFFFF & (b * 5)
        r = 0xFFFFFFFF & ((r << 7 | r >> 25) * 9)
        c = 0xFFFFFFFF & (c ^ a)
        d = 0xFFFFFFFF & (d ^ b)
        b = 0xFFFFFFFF & (b ^ c)
        a = 0xFFFFFFFF & (a ^ d)
        c = 0xFFFFFFFF & (c ^ t)
        d = 0xFFFFFFFF & (d << 11 | d >> 21)
        return r, (a, b, c, d)
    
    a,b,c,d = z3.BitVecs("a b c d", 64)
    nodiv_rand1, state = xoshiro128ss(a,b,c,d)
    nodiv_rand2, state = xoshiro128ss(*state)
    nodiv_rand3, state = xoshiro128ss(*state)
    nodiv_rand4, state = xoshiro128ss(*state)
    
    z3.solve(a >= 0, b >= 0, c >= 0, d >= 0,
      nodiv_rand1 == int(rand1*4294967296),
      nodiv_rand2 == int(rand2*4294967296),
      nodiv_rand3 == int(rand3*4294967296),
      nodiv_rand4 == int(rand4*4294967296)
      )
    
    

    I never heard about Z3

    If you’re not familiar with SMT solvers, they are a useful tool to have in your toolbox. Here are some links that may be of interest:

    Edit: Trying to fix formatting differences between kbin and lemmy
    Edit 2: Spoiler tags and code blocks don’t seem to play well together. I’ve got it mostly working on Lemmy (where I’m guessing most people will see the comment), but I don’t think I can fix it on kbin.


  • If I understand the problem correctly, this is the solution:

    solution

    a = 2299200278
    b = 2929959606
    c = 2585800174
    d = 3584110397

    I solved it with Z3. Took less than a second of computer time, and about an hour of my time – mostly spent trying to remember how the heck to use Z3 and then a little time debugging my initial program.


  • What I’d do is set up a simple website that uses a little JavaScript to rewrite the date and time into the page and periodically refresh an image under/next to it. Size the image to fit the remaining free space of however you set up the iPad, and then you can stick anything you want there (pictures/reminder text/whatever) with your favorite image editor. Upload a new image to the server when you want to change the note. The idea with an image is that it’s just really easy to do and keeps the amount of effort to redo layout to a minimum – just drag stuff around in your image editor and you’ll know it’ll all fit as expected as long as you don’t change the resolution (instead of needing to muck around with CSS and maybe breaking something if you can’t see the device to check that it displays correctly).

    There’s a couple issues to watch out for – e.g. what happens if the internet connection/server goes down, screen burn-in, keeping the browser from being closed/switched to another page, keeping it powered, etc. that might or might not matter depending on your particular circumstances. If you need to fix all that for your circumstances, it might be more trouble than just buying something purpose built… but getting a first pass DIY version working is trivial if you’re comfortable hosting a website.

    Edit: If some sample code that you can use as a starting point would be helpful, let me know.





  • Any ways to get around the download failing

    I did this incredibly stupid procedure with Firefox yesterday as a workaround for a failing Google Takeout download:

    • backup the .part file from the failed download
    • restart the download (careful – if you didn’t move/back it up, it will be deleted and you will have to download the whole thing again; found this out the hard way on a 50GB+ file… that failed again)
    • immediately pause the new download after it starts writing to disk
    • replace the new .part file with the old .part file from earlier (or – see [1] below)
    • Firefox might not show progress for a long time, but will eventually continue the download (I saw it reading the file back from disk with iotop so I just let it run)
    • sanity check that you actually got the whole thing and that it is usable (in my case, I knew a hash for the file)

    [1] You can actually replace the new .part file with anything that has the same size in bytes as the old file – I replaced it with a file full of zeros and manually merged the end onto the original .part file with a tiny custom python script since I had already moved the incomplete file to other media before realizing I could try this. (In my case, the incomplete file would still have been useful even with the last ~1MB cut off.)

    There are probably better options in most cases – like Thunderbird for mailbox as other people suggested, or rclone for getting stuff from Drive – but if you need to get Takeout to work and the download keeps failing this may be another option to try.


  • e0qdk@kbin.socialtoLinux@lemmy.mlOpenGL version problem
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    1 year ago
    • GLFW is intended to be built with cmake.
    • After unzipping the source, make a build directory, and configure glfw3
    • ^^ I like using ccmake to do this interactively, but you can also just pass flags to cmake if you know what they are
    • You should build with GLFW_USE_WAYLAND and GLFW_USE_OSMESA turned off to get it to try to build against X11.
    • You will probably also want to turn off GLFW_BUILD_DOCS, GLFW_BUILD_EXAMPLES, GLFW_BUILD_TESTS
    • You can adjust CMAKE_INSTALL_PREFIX if you don’t want to use the /usr/local default install path.
    • After generating a Makefile, run make and make install
    • glfw3 generates a pkg-config compatible .pc file as part of its build process that lists flags needed for compilation and linking against the library. Normally, you’d just call pkg-config --cflags --libs --static glfw3 to get this info as part of your own build process (in a Makefile, for example) or else require glfw3 as part of a cmake-based build, but you can read what’s generated in there if that program is not available to you for some reason. In case it’s helpful for comparison, what I get with a custom build of the static library version of glfw3 installed into /usr/local on a slightly old version of Ubuntu is output like -I/usr/local/include -L/usr/local/lib -lglfw -lrt -lm -ldl -lX11 -lpthread -lxcb -lXau -lXdmcp but you may need something different for your particular configuration.

    Basically, something like this, probably, to do the compilation and get the flags to pass to g++:

    wget 'https://github.com/glfw/glfw/releases/download/3.3.8/glfw-3.3.8.zip'
    unzip glfw-3.3.8.zip
    mkdir build
    cd build
    cmake -D GLFW_BUILD_DOCS=OFF -D GLFW_BUILD_EXAMPLES=OFF -D GLFW_BUILD_TESTS=OFF -D GLFW_USE_OSMESA=OFF -D GLFW_USE_WAYLAND=OFF -D GLFW_VULKAN_STATIC=OFF ../glfw-3.3.8
    make
    make install
    
    pkg-config --cflags --libs --static glfw3
    
    

    If you want to just compile a single cpp file after building and install, you can do something like

    g++ main.cpp `pkg-config --cflags --libs --static glfw3` -lGL
    
    


    • You are running Wayland
    • Your GLFW programs are using EGL, not GLX, to talk to your graphics drivers/hardware
    • glxinfo is talking to a software implementation, not your hardware
    • glxinfo’s output is irrelevant if you want to talk to your hardware with your current configuration; if you want to use the software implementation recompile GLFW targeting GLX and it should match that (but will be VERY slow).
    • One of your old posts describes your GPU as: Intel GMA3100 (G31) – is this the same system you’re running on now? If so, that is ancient. It looks like that came out in 2007 – which predates the existence of OpenGL 3.0; so, getting 2.1 as the newest context available when talking to actual hardware is not surprising…




  • If I understood your question correctly, you’d run the proxy application (which might be Squid or Apache or some other program) either on the host computer outside the VM or elsewhere on your network. (I’m not well versed on all the ins and outs of setting Firefox up to communicate through a proxy; I just know it can be done.) The proxy would listen for incoming traffic on a specific port you configure. You then tell Firefox (in its network settings) to communicate with the specific IP and port of the proxy instead of talking to web servers directly.

    To prevent other programs from communicating, you’d firewall off the VM with iptables (or maybe ufw or something else depending on what you use on your system). You’d set it to drop all traffic going to/from the VM’s network except packets going to or coming from the specific IP/port combinations you want to allow.

    This isn’t a bulletproof way to block other apps from talking to the internet – anything that knows about the proxy (or which can hijack/manipulate a program like Firefox that you’ve told about the proxy) could communicate with web servers via the proxy, but depending on your specific concerns it may be good enough.