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Extracting bits with a single multiplication
... Let's re-state the problem being asked as a theorem:
"There exists some 64-bit constants 'mask' and 'multiplicand' such that, for all 64-bit bitvectors x, in the expression y = (x & mask) * multiplicand, we have that y.63 == x.63, y.62 == x.55, y.61 == x.47, etc."
If this sentence is in fact...
How Big can a Python List Get?
...o Justen's answer indicates) that on other machines, notably those running 64-bit systems, the value of PY_SSIZE_T_MAX can very greatly.
– ClydeTheGhost
Aug 8 '16 at 18:46
...
What is the LD_PRELOAD trick?
...selinux.so.1.
> ldd /bin/ls
...
libselinux.so.1 => /lib/x86_64-linux-gnu/libselinux.so.1 (0x00007f3927b1d000)
libacl.so.1 => /lib/x86_64-linux-gnu/libacl.so.1 (0x00007f3927914000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f392754f000)
libpcre.so.3 => /l...
How to send a correct authorization header for basic authentication
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Per https://developer.mozilla.org/en-US/docs/Web/API/WindowBase64/Base64_encoding_and_decoding and http://en.wikipedia.org/wiki/Basic_access_authentication , here is how to do Basic auth with a header instead of putting the username and password in the URL. Note that this still doesn't h...
Error to install Nokogiri on OSX 10.9 Maverick?
...-I/Users/ericcamalionte/.rvm/rubies/ruby-1.9.2-p320/include/ruby-1.9.1/x86_64-darwin11.4.0 -I/Users/ericcamalionte/.rvm/rubies/ruby-1.9.2-p320/include/ruby-1.9.1/ruby/backward -I/Users/ericcamalionte/.rvm/rubies/ruby-1.9.2-p320/include/ruby-1.9.1 -I. -I/usr/local/Cellar/libxslt/1.1.28/include -I/usr...
How does java do modulus calculations with negative numbers?
Am I doing modulus wrong? Because in Java -13 % 64 is supposed to evaluate to -13 but I get 51 .
14 Answers
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How can I setup & run PhantomJS on Ubuntu?
... https://bitbucket.org/ariya/phantomjs/downloads/phantomjs-1.9.7-linux-x86_64.tar.bz2
sudo tar xjf phantomjs-1.9.7-linux-x86_64.tar.bz2
sudo ln -s /usr/local/share/phantomjs-1.9.7-linux-x86_64/bin/phantomjs /usr/local/share/phantomjs
sudo ln -s /usr/local/share/phantomjs-1.9.7-linux-x86_64/bin/phant...
How do I install Python OpenCV through Conda?
...
This worked fine with Anaconda 2.7 on Win10 64bit, whereas conda install opencv did not.
– Anton Schwaighofer
Apr 18 '16 at 12:34
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Converting numpy dtypes to native python types
...ype(pyval)) # <class 'float'>
# and similar...
type(np.float64(0).item()) # <class 'float'>
type(np.uint32(0).item()) # <class 'long'>
type(np.int16(0).item()) # <class 'int'>
type(np.cfloat(0).item()) # <class 'complex'>
type(np.datetime64(0, 'D').item()) ...
What belongs in an educational tool to demonstrate the unwarranted assumptions people make in C/C++?
...3: (106) Invalid instruction 0x00dd
printf crashes. "O_O"
gcc 4.4@x86_64-suse-linux
We like to think that:
..05 int has the size of pointers
but 'sizeof(int)==sizeof(void*)' is false.
..08 overshifting is okay
but '(1<<bits_per_int)==0' is false.
..09a minus shifts backwards
but '(t=-1,(...