blockchain – I cannot locate which bit coin wallet my funds have gone to

I sent bit coin from 2 external accounts to the same bit coin wallet which were completed on the 4th March 2021. My problem is that I do not know which wallets they have gone to. I cannot find these funds. Please can you help me.

I have the Blockchain report of the transaction but cannot analyse it apart from the bit coin address. One transaction has gone to BTH and other to BTC and one spent next to it and the other does not. What does all this mean and can I find my wallet name from this report or can go to a site like bit address but again I have NO experience in any of this. Please can someone help.

Billy

filesystems – Why go I get “dirty bit is set” when renaming mounted VeraCrypt volume using fatlabel?

Because it’s mounted.

The ‘dirty’ bit is set as soon as the filesystem is mounted, and cleared as soon as it’s unmounted.

In general, this could be somewhat dangerous, as the tool apparently assumes that you will only be using it on an unmounted filesystem. (Fortunately, changing the label of a FAT volume only touches a single dedicated directory entry so it is unlikely to conflict with other filesystem operations or cause corruption, but since the tool clearly hasn’t been designed for that, it is best to not use it this way.)

Some other Linux filesystem drivers have an ioctl which allows tools to change filesystem metadata on a mounted filesystem, e.g. btrfs/xfs have FS_IOC_SETFSLABEL. Others were specifically written to allow the label to be changed from under their nose, e.g. ext4 allows e2label to do this. But the vfat filesystem driver currently has neither of those.

linux – Chromium-browser 32 bit crashes with SIGSEGV in FcCacheOffsetsValid

I just installed a fresh copy of Xubuntu 18.04.5 i386 (32 bit, non UEFI, default kernel with PAE) on a 4 GB RAM, Intel Core i3-4030U machine.

Everything works perfectly, except for Chromium-browser: whenever I start it, I get a Segmentation fault.

I tried both the old version that comes with 18.04 and the latest one from canonical-chromium-builds PPA:

deb http://ppa.launchpad.net/canonical-chromium-builds/stage/ubuntu bionic main

Currently the latest build is 88.0.4324.182-0ubuntu0.18.04.1 and I’m waiting for the newer 89.0.4389.72-0ubuntu0.18.04.1 to be ready.

If I run it with -g I get a hint that the problem lies in FontConfig’s cache, So I rebuilt all caches with sudo fc-cache --really-force; fc-cache --really-force but the problem persists.

I ran out of options. What else can I try?

Reading symbols from /usr/lib/chromium-browser/chromium-browser...Reading symbols from /usr/lib/debug/.build-id/7a/87f89121582e6d2c18fed0c6465131ef7f6487.debug...done.
done.

(gdb) run

Starting program: /usr/lib/chromium-browser/chromium-browser 
(Thread debugging using libthread_db enabled)
Using host libthread_db library "/lib/i386-linux-gnu/libthread_db.so.1".
(New Thread 0xb4523b40 (LWP 4823))
(New Thread 0xb3bffb40 (LWP 4829))
(New Thread 0xb2646b40 (LWP 4830))
(New Thread 0xb1e45b40 (LWP 4831))
(New Thread 0xb12ffb40 (LWP 4832))
(New Thread 0xb0afeb40 (LWP 4833))
(New Thread 0xaf8feb40 (LWP 4835))
(New Thread 0xb00ffb40 (LWP 4834))
(New Thread 0xaeeffb40 (LWP 4836))

Thread 1 "chromium-browse" received signal SIGSEGV, Segmentation fault.
FcCacheOffsetsValid () at ../../third_party/fontconfig/src/src/fccache.c:886
886 ../../third_party/fontconfig/src/src/fccache.c: No such file or directory.

(gdb) backtrace

#0  FcCacheOffsetsValid () at ../../third_party/fontconfig/src/src/fccache.c:886
#1  FcDirCacheMapFd () at ../../third_party/fontconfig/src/src/fccache.c:987
#2  0x04793a6d in FcDirCacheMapHelper () at ../../third_party/fontconfig/src/src/fccache.c:1029
#3  0x0479399b in FcDirCacheProcess () at ../../third_party/fontconfig/src/src/fccache.c:404
#4  0x0479363d in IA__FcDirCacheLoad () at ../../third_party/fontconfig/src/src/fccache.c:1064
#5  0x0477958f in IA__FcDirCacheRead () at ../../third_party/fontconfig/src/src/fcdir.c:442
#6  0x0476fa30 in FcConfigAddDirList () at ../../third_party/fontconfig/src/src/fccfg.c:529
#7  0x0476f967 in IA__FcConfigBuildFonts () at ../../third_party/fontconfig/src/src/fccfg.c:563
#8  0x0477df61 in FcInitLoadOwnConfigAndFonts () at ../../third_party/fontconfig/src/src/fcinit.c:172
#9  IA__FcInitLoadConfigAndFonts () at ../../third_party/fontconfig/src/src/fcinit.c:183
#10 0x0476eb72 in FcConfigEnsure () at ../../third_party/fontconfig/src/src/fccfg.c:88
#11 FcConfigInit () at ../../third_party/fontconfig/src/src/fccfg.c:114
#12 0x047ff5fc in GlobalFontConfig () at ../../ui/gfx/linux/fontconfig_util.cc:30
#13 NoDestructor<> () at ../../base/no_destructor.h:54
#14 GetInstance () at ../../ui/gfx/linux/fontconfig_util.cc:60
#15 GetGlobalFontConfig () at ../../ui/gfx/linux/fontconfig_util.cc:132
#16 0x047f2556 in gfx::InitializeFonts() () at ../../ui/gfx/font_util.cc:29
#17 0x01ae2dcc in Initialize () at ../../content/browser/browser_main_runner_impl.cc:95
#18 0x01add537 in BrowserMain () at ../../content/browser/browser_main.cc:43
#19 0x038ba892 in RunBrowserProcessMain () at ../../content/app/content_main_runner_impl.cc:521
#20 RunServiceManager () at ../../content/app/content_main_runner_impl.cc:1008
#21 0x038ba451 in Run () at ../../content/app/content_main_runner_impl.cc:883
#22 0x038b7c30 in RunContentProcess () at ../../content/app/content_main.cc:372
#23 0x038b844b in ContentMain () at ../../content/app/content_main.cc:398
#24 0x00980019 in ChromeMain () at ../../chrome/app/chrome_main.cc:130
#25 0x0097ff1f in main () at ../../chrome/app/chrome_exe_main_aura.cc:17

(gdb) thread apply all backtrace

Thread 10 (Thread 0xaeeffb40 (LWP 4836)):
#0  0xb7fd7bb5 in __kernel_vsyscall ()
#1  0xb7915880 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0xaeefee4c)
    at ../sysdeps/unix/sysv/linux/futex-internal.h:88
#2  __pthread_cond_wait_common (abstime=0x0, mutex=0xaeefee0c, cond=0xaeefee24) at pthread_cond_wait.c:502
#3  __pthread_cond_wait (cond=0xaeefee24, mutex=0xaeefee0c) at pthread_cond_wait.c:655
#4  0x039ba41c in Wait () at ../../base/synchronization/condition_variable_posix.cc:79
#5  0x039bada4 in TimedWait () at ../../base/synchronization/waitable_event_posix.cc:211
#6  0x039ba9e1 in Wait () at ../../base/synchronization/waitable_event_posix.cc:157
#7  0x03930d4d in Run () at ../../base/message_loop/message_pump_default.cc:55
#8  0x03985a5c in Run () at ../../base/task/sequence_manager/thread_controller_with_message_pump_impl.cc:477
#9  0x03985b06 in non-virtual thunk to base::sequence_manager::internal::ThreadControllerWithMessagePumpImpl::Run(bool, base::TimeDelta) () at ../../base/synchronization/lock_impl.h:94
#10 0x03957bc5 in Run () at ../../base/run_loop.cc:124
#11 0x0399615c in base::Thread::Run(base::RunLoop*) () at ../../base/threading/thread.cc:311
#12 0x03996331 in ThreadMain () at ../../base/threading/thread.cc:382
#13 0x039be0eb in ThreadFunc () at ../../base/threading/platform_thread_posix.cc:87
#14 0xb790f3bd in start_thread (arg=0xaeeffb40) at pthread_create.c:463
#15 0xb618dc96 in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:108

Thread 9 (Thread 0xb00ffb40 (LWP 4834)):
#0  0xb7fd7bb5 in __kernel_vsyscall ()
#1  0xb61860d3 in __GI___select (nfds=25, readfds=0xb00fef80, writefds=0x0, exceptfds=0x0, timeout=0x0)
    at ../sysdeps/unix/sysv/linux/select.c:41
#2  0x039c0508 in ThreadMain () at ../../base/files/file_path_watcher_linux.cc:276
#3  0x039be0eb in ThreadFunc () at ../../base/threading/platform_thread_posix.cc:87
#4  0xb790f3bd in start_thread (arg=0xb00ffb40) at pthread_create.c:463
#5  0xb618dc96 in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:108

Thread 8 (Thread 0xaf8feb40 (LWP 4835)):
#0  0xb7fd7bb5 in __kernel_vsyscall ()
#1  0xb618e0e3 in epoll_wait (epfd=26, events=0xa4ef1a0, maxevents=32, timeout=-1)
    at ../sysdeps/unix/sysv/linux/epoll_wait.c:30
#2  0x03b25071 in epoll_dispatch () at ../../base/third_party/libevent/epoll.c:198
#3  0x03b22cf2 in event_base_loop () at ../../base/third_party/libevent/event.c:512
#4  0x039d1091 in Run () at ../../base/message_loop/message_pump_libevent.cc:260
#5  0x03985a5c in Run () at ../../base/task/sequence_manager/thread_controller_with_message_pump_impl.cc:477
#6  0x03985b06 in non-virtual thunk to base::sequence_manager::internal::ThreadControllerWithMessagePumpImpl::Run(bool, base::TimeDelta) () at ../../base/synchronization/lock_impl.h:94
#7  0x03957bc5 in Run () at ../../base/run_loop.cc:124
#8  0x0399615c in base::Thread::Run(base::RunLoop*) () at ../../base/threading/thread.cc:311
#9  0x01ae49e8 in content::BrowserProcessSubThread::IOThreadRun(base::RunLoop*) ()
    at ../../content/browser/browser_process_sub_thread.cc:144
#10 0x03996331 in ThreadMain () at ../../base/threading/thread.cc:382
#11 0x039be0eb in ThreadFunc () at ../../base/threading/platform_thread_posix.cc:87
#12 0xb790f3bd in start_thread (arg=0xaf8feb40) at pthread_create.c:463
#13 0xb618dc96 in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:108

Thread 7 (Thread 0xb0afeb40 (LWP 4833)):
#0  0xb7fd7bb5 in __kernel_vsyscall ()
#1  0xb7915dd6 in futex_reltimed_wait_cancelable (private=<optimized out>, reltime=0xb0afddb0, expected=0, 
    futex_word=0xb0afdefc) at ../sysdeps/unix/sysv/linux/futex-internal.h:142
#2  __pthread_cond_wait_common (abstime=0xb0afde40, mutex=0xb0afdebc, cond=0xb0afded4)
    at pthread_cond_wait.c:533
#3  __pthread_cond_timedwait (cond=0xb0afded4, mutex=0xb0afdebc, abstime=0xb0afde40)
    at pthread_cond_wait.c:667
#4  0x039ba551 in TimedWait () at ../../base/synchronization/condition_variable_posix.cc:131
#5  0x039badc5 in TimedWait () at ../../base/synchronization/waitable_event_posix.cc:213
#6  0x03a03352 in WaitForWork () at ../../base/task/thread_pool/worker_thread.cc:36
#7  0x03a03b4d in RunWorker () at ../../base/task/thread_pool/worker_thread.cc:321
#8  0x03a039be in base::internal::WorkerThread::RunPooledWorker() ()
    at ../../base/task/thread_pool/worker_thread.cc:223
#9  0x03a0387e in ThreadMain () at ../../base/task/thread_pool/worker_thread.cc:203
#10 0x039be0eb in ThreadFunc () at ../../base/threading/platform_thread_posix.cc:87
#11 0xb790f3bd in start_thread (arg=0xb0afeb40) at pthread_create.c:463
#12 0xb618dc96 in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:108

Thread 6 (Thread 0xb12ffb40 (LWP 4832)):
#0  0xb7fd7bb5 in __kernel_vsyscall ()
#1  0xb7915dd6 in futex_reltimed_wait_cancelable (private=<optimized out>, reltime=0xb12fedb0, expected=0, 
    futex_word=0xb12feefc) at ../sysdeps/unix/sysv/linux/futex-internal.h:142
#2  __pthread_cond_wait_common (abstime=0xb12fee40, mutex=0xb12feebc, cond=0xb12feed4)
    at pthread_cond_wait.c:533
#3  __pthread_cond_timedwait (cond=0xb12feed4, mutex=0xb12feebc, abstime=0xb12fee40)
    at pthread_cond_wait.c:667
#4  0x039ba551 in TimedWait () at ../../base/synchronization/condition_variable_posix.cc:131
#5  0x039badc5 in TimedWait () at ../../base/synchronization/waitable_event_posix.cc:213
#6  0x03a03352 in WaitForWork () at ../../base/task/thread_pool/worker_thread.cc:36
#7  0x03a03dd2 in RunWorker () at ../../base/task/thread_pool/worker_thread.cc:345
#8  0x03a039be in base::internal::WorkerThread::RunPooledWorker() ()
    at ../../base/task/thread_pool/worker_thread.cc:223
#9  0x03a0387e in ThreadMain () at ../../base/task/thread_pool/worker_thread.cc:203
#10 0x039be0eb in ThreadFunc () at ../../base/threading/platform_thread_posix.cc:87
#11 0xb790f3bd in start_thread (arg=0xb12ffb40) at pthread_create.c:463
#12 0xb618dc96 in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:108

Thread 5 (Thread 0xb1e45b40 (LWP 4831)):
#0  0xb7fd7bb5 in __kernel_vsyscall ()
#1  0xb7915dd6 in futex_reltimed_wait_cancelable (private=<optimized out>, reltime=0xb1e44db0, expected=0, 
    futex_word=0xb1e44efc) at ../sysdeps/unix/sysv/linux/futex-internal.h:142
#2  __pthread_cond_wait_common (abstime=0xb1e44e40, mutex=0xb1e44ebc, cond=0xb1e44ed4)
    at pthread_cond_wait.c:533
#3  __pthread_cond_timedwait (cond=0xb1e44ed4, mutex=0xb1e44ebc, abstime=0xb1e44e40)
    at pthread_cond_wait.c:667
#4  0x039ba551 in TimedWait () at ../../base/synchronization/condition_variable_posix.cc:131
#5  0x039badc5 in TimedWait () at ../../base/synchronization/waitable_event_posix.cc:213
#6  0x03a03352 in WaitForWork () at ../../base/task/thread_pool/worker_thread.cc:36
#7  0x03a03dd2 in RunWorker () at ../../base/task/thread_pool/worker_thread.cc:345
#8  0x03a039be in base::internal::WorkerThread::RunPooledWorker() ()
    at ../../base/task/thread_pool/worker_thread.cc:223
#9  0x03a0387e in ThreadMain () at ../../base/task/thread_pool/worker_thread.cc:203
#10 0x039be0eb in ThreadFunc () at ../../base/threading/platform_thread_posix.cc:87
#11 0xb790f3bd in start_thread (arg=0xb1e45b40) at pthread_create.c:463
#12 0xb618dc96 in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:108

Thread 4 (Thread 0xb2646b40 (LWP 4830)):
#0  0xb7fd7bb5 in __kernel_vsyscall ()
#1  0xb618e0e3 in epoll_wait (epfd=19, events=0xb15012e0, maxevents=32, timeout=90000)
    at ../sysdeps/unix/sysv/linux/epoll_wait.c:30
#2  0x03b25071 in epoll_dispatch () at ../../base/third_party/libevent/epoll.c:198
#3  0x03b22cf2 in event_base_loop () at ../../base/third_party/libevent/event.c:512
#4  0x039d114b in Run () at ../../base/message_loop/message_pump_libevent.cc:260
#5  0x03985a5c in Run () at ../../base/task/sequence_manager/thread_controller_with_message_pump_impl.cc:477
#6  0x03985b06 in non-virtual thunk to base::sequence_manager::internal::ThreadControllerWithMessagePumpImpl::Run(bool, base::TimeDelta) () at ../../base/synchronization/lock_impl.h:94
#7  0x03957bc5 in Run () at ../../base/run_loop.cc:124
#8  0x0399615c in base::Thread::Run(base::RunLoop*) () at ../../base/threading/thread.cc:311
#9  0x039ff095 in base::internal::ServiceThread::Run(base::RunLoop*) ()
    at ../../base/task/thread_pool/service_thread.cc:54
#10 0x03996331 in ThreadMain () at ../../base/threading/thread.cc:382
#11 0x039be0eb in ThreadFunc () at ../../base/threading/platform_thread_posix.cc:87
#12 0xb790f3bd in start_thread (arg=0xb2646b40) at pthread_create.c:463
#13 0xb618dc96 in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:108

Thread 3 (Thread 0xb3bffb40 (LWP 4829)):
#0  0xb7fd7bb5 in __kernel_vsyscall ()
#1  0xb791aeb7 in __waitpid (pid=4826, stat_loc=0xb3bfefe8, options=0)
    at ../sysdeps/unix/sysv/linux/waitpid.c:28
#2  0x039b90f7 in WaitpidWithTimeout () at ../../base/process/process_posix.cc:62
#3  WaitForExitWithTimeoutImpl () at ../../base/process/process_posix.cc:209
#4  WaitForExitWithTimeout () at ../../base/process/process_posix.cc:356
#5  0x039b939e in WaitForExit () at ../../base/process/process_posix.cc:342
#6  0x039b6df3 in ThreadMain () at ../../base/process/kill_posix.cc:141
#7  0x039be0eb in ThreadFunc () at ../../base/threading/platform_thread_posix.cc:87
#8  0xb790f3bd in start_thread (arg=0xb3bffb40) at pthread_create.c:463
#9  0xb618dc96 in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:108

Thread 2 (Thread 0xb4523b40 (LWP 4823)):
#0  0xb7fd7bb5 in __kernel_vsyscall ()
#1  0xb61834eb in __GI___poll (fds=0xb4523010, nfds=2, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#2  0x020e7abd in Run () at ../../content/browser/sandbox_ipc_linux.cc:47
#3  0x039957f6 in base::DelegateSimpleThread::Run() () at ../../base/threading/simple_thread.cc:98
#4  0x03995655 in base::SimpleThread::ThreadMain() () at ../../base/threading/simple_thread.cc:75
#5  0x039be0eb in ThreadFunc () at ../../base/threading/platform_thread_posix.cc:87
#6  0xb790f3bd in start_thread (arg=0xb4523b40) at pthread_create.c:463
#7  0xb618dc96 in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:108

Thread 1 (Thread 0xb513bc40 (LWP 4804)):
#0  FcCacheOffsetsValid () at ../../third_party/fontconfig/src/src/fccache.c:886
#1  FcDirCacheMapFd () at ../../third_party/fontconfig/src/src/fccache.c:987
#2  0x04793a6d in FcDirCacheMapHelper () at ../../third_party/fontconfig/src/src/fccache.c:1029
#3  0x0479399b in FcDirCacheProcess () at ../../third_party/fontconfig/src/src/fccache.c:404
#4  0x0479363d in IA__FcDirCacheLoad () at ../../third_party/fontconfig/src/src/fccache.c:1064
#5  0x0477958f in IA__FcDirCacheRead () at ../../third_party/fontconfig/src/src/fcdir.c:442
#6  0x0476fa30 in FcConfigAddDirList () at ../../third_party/fontconfig/src/src/fccfg.c:529
#7  0x0476f967 in IA__FcConfigBuildFonts () at ../../third_party/fontconfig/src/src/fccfg.c:563
#8  0x0477df61 in FcInitLoadOwnConfigAndFonts () at ../../third_party/fontconfig/src/src/fcinit.c:172
#9  IA__FcInitLoadConfigAndFonts () at ../../third_party/fontconfig/src/src/fcinit.c:183
#10 0x0476eb72 in FcConfigEnsure () at ../../third_party/fontconfig/src/src/fccfg.c:88
#11 FcConfigInit () at ../../third_party/fontconfig/src/src/fccfg.c:114
#12 0x047ff5fc in GlobalFontConfig () at ../../ui/gfx/linux/fontconfig_util.cc:30
#13 NoDestructor<> () at ../../base/no_destructor.h:54
#14 GetInstance () at ../../ui/gfx/linux/fontconfig_util.cc:60
#15 GetGlobalFontConfig () at ../../ui/gfx/linux/fontconfig_util.cc:132
#16 0x047f2556 in gfx::InitializeFonts() () at ../../ui/gfx/font_util.cc:29
#17 0x01ae2dcc in Initialize () at ../../content/browser/browser_main_runner_impl.cc:95
#18 0x01add537 in BrowserMain () at ../../content/browser/browser_main.cc:43
#19 0x038ba892 in RunBrowserProcessMain () at ../../content/app/content_main_runner_impl.cc:521
#20 RunServiceManager () at ../../content/app/content_main_runner_impl.cc:1008
#21 0x038ba451 in Run () at ../../content/app/content_main_runner_impl.cc:883
#22 0x038b7c30 in RunContentProcess () at ../../content/app/content_main.cc:372
#23 0x038b844b in ContentMain () at ../../content/app/content_main.cc:398
#24 0x00980019 in ChromeMain () at ../../chrome/app/chrome_main.cc:130
#25 0x0097ff1f in main () at ../../chrome/app/chrome_exe_main_aura.cc:17

(gdb) 

Can someone explain virtual adapters a bit more in depth?

I do know that virtual adapters are used by virtual machines and vpn, but I don’t understand how they actually work:

  1. Once a virtual adapter is created, is it some kind of pure software independent of a physical nic just running by os? or is it located inside the nic, taking part from physical hardware?

  2. If I don’t have a physical adapter, can I still create a virtual one to communicate with my virtual machines

  3. Simple explanation of how it works or at least some resourses to read about it, obiously I’ve been searching but there is just really basic descriptions which doesn’t help much

bit manipulation – Shift Operation with Shifted Bits Greater Than or Equal To the Operand’s

In Computer Systems A Programmer’s Perspective (3rd Edition), the author says, “For a data type consisting of w bits, if we shift by some value k (k ≥ w), on many machines we eventually shift the data type by k mod w bits.” However, when I code with C, like this and run on my laptop (x86-64, Windows 10):

#include <stdio.h>
int main() {
    unsigned char c = 0b01100010;
    c <<= 8;
    printf("%x", c);
    return 0;
}

The result is 0, which means it really shifted by 8 bits, but if we consider that w is 8 and k is 8, in this case the machine would shift by nothing (since 8 mod 8 == 0) and it is supposed to get the original value c. Why did this happen?

Las Vegas algorithm for finding 00000 in bit string

Problem 1: Consider the following problem: given a binary string $w=a_1a_2cdots a_n in{0,1}^*$, decide whether $w$ contains 00000 as a substring (i.e., where $w$ contains five consecutive 0’s). There is an obvious $O(n)$-time algorithm. You will investigate the hidden constant factor, concerning the number of bits that need to be examined (i.e., the number of $a_i$‘s that need to be evaluated) to solve this problem.

  1. (10/100 points) First argue that every deterministic algorithm solving this problem needs to evaluate $Omega(n)$ bits in the worst case.
  2. (30/100 points) Prove that for a sufficiently large constant $c$, for any string $a_1 cdots a_c$ of length $c$ that does not contain 00000, there must exist two indices $i,j in {1,ldots,c}$ with $a_i=a_j=1$ and $2 leq |i-j| leq 5$.
  3. (60/100 points) Design a Las Vegas randomized algorithm solving this problem (with zero error probability) that evaluates an expected $alpha n + o(n)$ number of bits for any input, for some constant $alpha$ strictly smaller than $1$. (You do not need to optimize the constant $alpha$.)

Above is a question some friends and I have looked at to prepare for a qualifying exam and is itself from a past qualifying exam. Parts 1 and 2 are fine but what we are having troubles with is part 3. I think the idea behind this problem is to imagine that evaluating some bit $s_i$ is really expensive, so we would like to get the right answer while minimizing how many of these bits we evaluate. That said, there is some ambiguity to us about whether we (1) care about the number of distinct bits we evaluate or (2) the total number of times we evaluate any bit. Clearly if we were worried about the latter, we could just store the result of the bit evaluation and avoid doing an expensive evaluation again, but we are not sure. For now, I assume the latter case and specifically that if we want the value for the same bit twice, we assume we need to evaluate it each time and incur $2$ units to the cost we are trying to minimize.


Now I have some idea for this problem and to help explain my idea, let us consider a simple deterministic algorithm with the pseudocode written below. We will loop from the start of the string to the end, checking all meaningful 5 bit substrings. If we ever find a $1$ bit as we loop over a 5 bit substring, we know that substring cannot be $00000$ but if we start at the bit right after that $1$ bit, there might be one. Thus, we update our new starting point to the position right after that $1$ bit and then start back up again from there.

On input $s$:

  1. set $i leftarrow 1$
  2. while($i leq (n-4)$):
    • set $b leftarrow text{true}$
    • for($j = 0$ to $4$):
      • if( $a_{i+j} = 1$ ):
        • $i leftarrow (i+j+1)$
        • $b leftarrow text{false}$
        • break for loop.
    • if( $b = text{true}$ ):
  3. return FALSE

My idea for a Las Vegas algorithm was to do the same algorithm but slightly modify it by making the inner loop performed in random order, making the pseudocode now be

On input $s$:

  1. set $i leftarrow 1$
  2. while($i leq (n-4)$):
    • set $b leftarrow text{true}$
    • for($j = 0$ to $4$ in random order):
      • if( $a_{i+j} = 1$ ):
        • $i leftarrow (i+j+1)$
        • $b leftarrow text{false}$
        • break for loop.
    • if( $b = text{true}$ ):
  3. return FALSE

The positive thing going for this algorithm is that if there exists a $1$ bit in the 5 bit substring we are looking at in the inner loop, we will find it in at most $3$ loop iterations in expectation. However, if I define a bit string $s$ to be
$$s = 100001 100001 100001 cdots 100001$$
then the algorithm should require looking at $6$ bits (potentially some of the same ones multiple times) in expectation to get past each $100001$ substring. This implies on this input we will go to see the value of $n$ bits (the number of distinct bits seen may be less) in expectation before we answer the question of if $00000$ is contained in $s$. Thus, this algorithm does not seem sufficient.

Does anyone have any thoughts on how to approach this problem or think we should actually be worried about the number of distinct bits we evaluate? If yes to the latter, then I could potentially see other ways to tackle this problem.

A bit of anal niche

analtime.org
Check out this site, dudes … how do you like it?
maybe you have a recommendation. (for example, how to get rid of Turkish traffic xD)

python – Classes – something ive found a ton of resources about, but cannot understand this specific bit

to preface this, I have searched and read so much, I understand (I think….) methods, classes and functions.

What I am trying to wrap myhead around is… a class is essentially a blueprint…? using humans as an example, I create a Human class, and within this class I have different functions based on name, age and height.

class Human():

    def __init__ (self):
        return

    def name(self,name):
        self.name

    def age(self, age):
        self.age

    def height(self,height):
        self.height

    def person (self,name,age,height):
        return f'Hello, my name is {self.name}, I am {self.age} and {self.height} Tall'

Then I want to create two (or as many as I want) humans. So i create an instance of the human class as the blueprint….

import mod

people = mod.Human()

so now I want to create my two people (that are humans and should have a name, age and height associated with them)…

Liam = people.person('liam', 28, "6'" '2"')
Tori = people.person('Tori', 29, "5'" '8"')

So at this point, is my understanding of classes/functions and my utlization of them correct?

print(Liam)

When I print this out I get;

Hello, my name is <bound method Human.name of <mod.Human object at 0x0353E628>>, I am <bound method Human.age of <mod.Human object at 0x0353E628>> and <bound method Human.height of <mod.Human object at 0x0353E628>> Tall

I had this bit working earlier when I created my person through two lines of code instead of one. But this isnt what I was after (one line per person created is what I am after).

class Human:

    def __init__(self, name, age, height):
        self.name = name
        self.age = age
        self.height = height

    def person (self):
        return f'Hello, my name is:  {self.name}, I am {self.age} and {self.height} Tall'

import mod

liam = mod.Human('liam', 28, "6'" '2"')
LiamFull = liam.person()

print(LiamFull)

Hello, my name is:  liam, I am 28 and 6'2" Tall

Gamma Correction and Shadow Detail bit allocation

I’m having slight difficulties understanding how a gamma correction increases details in the shadows(where our eyes are more sensitive). Once the bits have been been reallocated to the shadows after applying an INVERSE GAMMA/GAMMA CORRECTION in the camera wouldn’t all that detail just be lost as the monitor would apply a GAMMA to counter the inverse gamma thus bringing the image luminance back to a linear function. Or are the code values saved after gamma correction and only the brightness is brought down.

I’ll use an example I took from the video “Diving into dynamic range” from Filmmaker IQ on youtube.

From what I understood, in his example he uses an 8 STOP(the triangles represent the stops) camera with an 8 bit depth(Not exactly sure about this I got abit confused here. Please correct me If I’m wrong)

enter image description here

enter image description here

Basically once the GAMMA of the screen is applied to the above OETF GAMMA curve and it goes back to the LINEAR one why wouldn’t we loose all the details in the shadow again??

Here’s the link to the video just in case: https://www.youtube.com/watch?v=2sshGdMgJxQ

Home lost power for a bit, now I can’t access next cloud or ovpn on my ubuntu server

I am completely new to Lunix/Ubuntu so bear with me.
Last month I took a desktop and installed Ubuntu 20.
I installed OVPN and Next Cloud. I have a dedicated IP from my ISP.
Everything was working properly, auto uploading my files to next cloud.
This week my house lost power. Now my server is up, but I can get to my next cloud and OVPN isn’t authenticating.

I tried to force the services, but don’t know if I am doing it correctly or how to even verify they are running beside trying to access the nextcloud web gui.