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Although probably known in most circles, it is worth repeating that scp by itself does not honor symbolic links. To overcome this limitation just combine tar and ssh, i.e., tar on sending side, untar on receiving side: tar cf - /src/dir | ssh remotehost "cd /dst/dir ; tar xf -" Usually…
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Average Size of Web Pages plus Prediction shows an exponential fitting to web-page sizes. From above article: As you can see, the 1/2 MB mark was cracked in 2009 and the 1 MB mark was cracked in 2012. Despite the seemingly random fluctuations, an exponential trend is clearly visible. The power…
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A colleague of mine noticed some strange behaviours in his programs. It was later discovered that this is due to SyncSort not conducting a stable sort. Stable sort means that the sequence of elements in input is not changed if there is no strict need to change them. Unfortunately, the documentation…
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Some statistics from WordPress just for month July, 2013. These sheer numbers almost sound unbelievable: 1 million new blogs 7 Exabyte of data 1 billion pages accessed by mobile devices 9 million YouTube videos embedded 500.000 posts per e-mail 200 posts per voice
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For the numerical solution of the ordinary differential equation, initial value problem $$ y'=f(t,y), \quad y(t_0)=y_0,$$ one can use a cyclic composite multistep method of the form $$ \sum\limits_{i=0}^{m} A_i Y_{k+i} = h \sum\limits_{i=0}^{m} B_i Y'_{k+i}, \qquad…
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I got somewhat tired of using FTP with my Android, even with lftp. Keeping multiple folders in sync is simply very cumbersome. If I only had rsync working on Android! I found SSHelper, written by Paul Lutus, see also Arachnoid. SSHelper offers ssh, scp, rsync. You can ssh to your Android phone and…
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When visiting Harvard University I received an Emergency Alert directly on my phone, see below. Google Now Emergency Alert At first I thought that this was a kind of student hack, but others just received the same alerts. After inspection it contained additional information, shown below. Flood…
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Lawrence Livermore National Laboratory provides a suite of software packages for the solution of ordinary differential equations. This suite is called SUNDIALS. SUNDIALS consists of CVODE: solves initial value problems for ordinary differential equation (ODE) systems; successor of GEAR, EPISODE,…
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HipHop Virtual Machine says that HHVM can run WordPress. A more technical description of the HHVM can be found in Speeding up PHP-based development with HipHop VM. One of the main targets was to be as fast as the previous PHP to C++ translater. This goal has been achieved, see below…
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Gunnar Heinsohn (German Wikipedia, English Wikipedia) wrote a book with title Söhne und Weltmacht -- Terror im Aufstieg und Fall der Nationen in German. This book is about: youth bulge and its implication to criminal or war activity genocide property and possession This book can explain why…
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My recent project had some issues with hashing some 10 million numbers. To analyze the matter I wrote a small test program, see numberhash.c. I wanted to know which influence the following factors play: hashing just numbers (no alphabetic characters) ASCII vs. EBCIDC choice of hash function load…
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Here is a simple test program to call SHA1 hashing routine from OpenSSL. #include <stdio.h> #include <string.h> #include <openssl/sha.h> int main (int argc, char *argv[]) { unsigned long i, n; unsigned char md[1024]; if (argc <= 1) return 0; n…
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Peter Kankowski wrote a very interesting article on hashing functions. It compares a number of current hash functions and conducts some performance benchmarks. iSCSI CRC Meiyan Murmur2 XXHfast32 SBox (dead link: https://home.comcast.net/~bretm/hash/10.html) Larson XXHstrong32 Sedgewick Novak…
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Here is an article GNU C: Extensions to the C Language Family about extensions in GNU C vs. ANSI C. Nested functions, i.e., a function defined within another function Double-word integers, i.e., 64 bit signed and unsigned long long int and unsigned long long int Arrays of variable length, f(int z)…
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Recently I learned the hard way that IBM Enterprise COBOL compiler for z/OS (mainframe) cannot generate 8-byte long POINTER variables, but only 4-byte pointers. This means, you cannot use more than 2GB in COBOL on a mainframe. I.e., you cannot make use of AMODE=64 with COBOL on the mainframe. You…
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Generators (and therefore coroutines) are now part of PHP (Wikipedia) 5.5, as of 20-Jun-2013. Here is an example: function xrange($start,$end) { for ($i = $start; $i<=$end; ++$i) yield($i); } The Icon programming language (Wikipeda) was one of the first computer languages where…
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I read a short note in Heise, that in 2011 WordPress was one of the most popular CMS. The report compared Alfresco WCM CMSMadeSimple Concrete5 DotNetNuke Drupal e107 eZ Publish Joomla! Liferay MODx Movable Type OpenCms Plone SilverStripe Textpattern Tiki Wiki CMS…
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I ran below commands under different load for my Gigabyte GTX 560 graphic card. export LD_LIBRARY_PATH=$CUDA_PATH/lib64 time /usr/local/cuda/samples/sdk/0_Simple/matrixMul/matrixMul time /usr/local/cuda/samples/sdk/0_Simple/matrixMulCUBLAS/matrixMulCUBLAS I was interested in the value…
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I copy Brian Koberlein's explanations on the history of Kepler's law. Kepler’s first two rules, that the orbit of a planet is an ellipse, and that a line drawn from the Sun to a planet sweeps out area at a constant rate were proposed in 1609. While these rules allowed for a more accurate…
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There is a an INCITE program (HPC Call for Proposals), where one can apply for CPU/GPU intensive jobs, the link is INCITE. From the FAQ: The INCITE program is open to US- and non-US-based researchers and research organizations needing large allocations of computer time, supporting resources, and…