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  • Signal processing or algorithmic programming for a PLC

    - by james singen smythe
    I have an application that takes voltages and temperatures as analog inputs and does some processing using an algorithm which involves signal processing such as low-pass filtering, exponential smoothing, and other steps which might typically be done in a high-level programming language such as C or C++. I'm curious how I could perform these same steps using a PLC, and in particular, the Allen-Bradley Control-Logix system? It seems to me that the instruction set with ladder logic is too limited for this. Could I perform this using structured text?

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  • set environment variables calling script file

    - by sandeep
    I have a requirement where I have to set environment variables calling a script file eg:set_env.sh. set_env.sh contains all the environment variables. export SCRIPT_DIR=/e/scripts/ ... when I call the set_env.sh from my code the variables are available in that file itself. They are not available in file where I have called the script. What should be done so that environment variables can be retained and can be used in file which calls set_env.sh. Thanks, Sandeep M.

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  • Looking for fastest and least-programming-required path to implement a web site with user submitted

    - by Howiecamp
    I'm looking to throw up a web site that supports user submitted entries and allows voting and comments. Similar in form and function to FMyLife. Basic requirements of site: Users can submit text entries - generally 1 liners Enters can be up or down voted Comments allowed - presentation collapseable Would like the fastest path possible. Ideal solution is configurable vs requirement for programming.

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  • Practical Uses of Fractals in Programming

    - by Sami
    Fractals have always been a bit of a mystery for me. What practical uses (beyond rendering to beautiful images) are there for fractals in the various programming problem domains? And please, don't just list areas that use them. I'm interested in specific algorithms and how fractals are used with those algorithms to solve something in practice. Please at least give a short description of the algorithm.

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  • Using pthread to perform matrix multiplication

    - by shadyabhi
    I have both matrices containing only ones and each array has 500 rows and columns. So, the resulting matrix should be a matrix of all elements having value 500. But, I am getting res_mat[0][0]=5000. Even other elements are also 5000. Why? #include<stdio.h> #include<pthread.h> #include<unistd.h> #include<stdlib.h> #define ROWS 500 #define COLUMNS 500 #define N_THREADS 10 int mat1[ROWS][COLUMNS],mat2[ROWS][COLUMNS],res_mat[ROWS][COLUMNS]; void *mult_thread(void *t) { /*This function calculates 50 ROWS of the matrix*/ int starting_row; starting_row = *((int *)t); starting_row = 50 * starting_row; int i,j,k; for (i = starting_row;i<starting_row+50;i++) for (j=0;j<COLUMNS;j++) for (k=0;k<ROWS;k++) res_mat[i][j] += (mat1[i][k] * mat2[k][j]); return; } void fill_matrix(int mat[ROWS][COLUMNS]) { int i,j; for(i=0;i<ROWS;i++) for(j=0;j<COLUMNS;j++) mat[i][j] = 1; } int main() { int n_threads = 10; //10 threads created bcos we have 500 rows and one thread calculates 50 rows int j=0; pthread_t p[n_threads]; fill_matrix(mat1); fill_matrix(mat2); for (j=0;j<10;j++) pthread_create(&p[j],NULL,mult_thread,&j); for (j=0;j<10;j++) pthread_join(p[j],NULL); printf("%d\n",res_mat[0][0]); return 0; }

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  • Perl open call failing.

    - by benjamin button
    I am new to perl coding. I am facing a problem while executing a small script i have: open is not able to find the file which i am giving as an argument.Please see below: File is available: ls -l DLmissing_months.sql -rwxr-xr-x 1 tlmwrk61 aimsys 2842 May 16 09:44 DLmissing_months.sql My perl script: #!/usr/local/bin/perl use strict; use warnings; my $this_line = ""; my $do_next = 0; my $file_name = $ARGV[0]; open( my $fh, '<', '$file_name') or die "Error opening file - $!\n"; close($fh); executing the perl script : > new.pl DLmissing_months.sql Error opening file - No such file or directory what is the problem with my perl script.

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  • Replacing Part of Text Using Sed

    - by neversaint
    I have the following text file Eif2ak1.aSep07 Eif2ak1.aSep07 LOC100042862.aSep07-unspliced NADH5_C.0.aSep07-unspliced LOC100042862.aSep07-unspliced NADH5_C.0.aSep07-unspliced What I want to do is to remove all the text starting from period (.) to the end. But why this command doesn't do it? sed 's/\.*//g' myfile.txt What's the right way to do it?

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  • How to do a join of 3 files with awk by first Column?

    - by noinflection
    i have three similar files, they are all like this: ID1 Value1a ID2 Value2a . . . IDN Value2n and i want an output like this ID1 Value1a Value1b Value1c ID2 Value2a Value2b Value2c ..... IDN ValueNa ValueNb ValueNc Looking to the first line i want value1A to be the value of id1 in fileA, value1B the value of id1 in fileB, etc, i think of it like a nice sql join. I've tried several things but none of them where even close.

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  • Get directory path by fd

    - by tylerl
    I've run into the need to be able refer to a directory by path given its file descriptor in Linux. The path doesn't have to be canonical, it just has to be functional so that I can pass it to other functions. So, taking the same parameters as passed to a function like fstatat(), I need to be able to call a function like getxattr() which doesn't have a f-XYZ-at() variant. So far I've come up with these solutions; though none are particularly elegant. The simplest solution is to avoid the problem by calling openat() and then using a function like fgetxattr(). This works, but not in every situation. So another method is needed to fill the gaps. The next solution involves looking up the information in proc: if (!access("/proc/self/fd",X_OK)) { sprintf(path,"/proc/self/fd/%i/",fd); } This, of course, totally breaks on systems without proc, including some chroot environments. The last option, a more portable but potentially-race-condition-prone solution, looks like this: DIR* save = opendir("."); fchdir(fd); getcwd(path,PATH_MAX); fchdir(dirfd(save)); closedir(save); The obvious problem here is that in a multithreaded app, changing the working directory around could have side effects. However, the fact that it works is compelling: if I can get the path of a directory by calling fchdir() followed by getcwd(), why shouldn't I be able to just get the information directly: fgetcwd() or something. Clearly the kernel is tracking the necessary information. So how do I get to it?

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  • Converting FASTQ to FASTA with SED/AWK

    - by neversaint
    I have a data in that always comes in block of four in the following format (called FASTQ): @SRR018006.2016 GA2:6:1:20:650 length=36 NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNGN +SRR018006.2016 GA2:6:1:20:650 length=36 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!+! @SRR018006.19405469 GA2:6:100:1793:611 length=36 ACCCGCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC +SRR018006.19405469 GA2:6:100:1793:611 length=36 7);;).;);;/;*.2>/@@7;@77<..;)58)5/>/ Is there a simple sed/awk/bash way to convert them into this format (called FASTA): >SRR018006.2016 GA2:6:1:20:650 length=36 NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNGN >SRR018006.19405469 GA2:6:100:1793:611 length=36 ACCCGCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC In principle we want to extract the first two lines in each block-of-4 and replace @ with >.

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  • Sending the command(s) spawned by xargs to background

    - by PoorLuzer
    I want to know how I can send the command(s) spawned by xargs to background. For example, consider find . -type f -mtime +7 | tee compressedP.list | xargs compress I tried find . -type f -mtime +7 | tee compressedP.list | xargs -i{} compress {} & .. and as unexpected, it seems to send xargs to the background instead? How do I make each instance of the compress command go to the background?

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  • bash and flock (file lock) - Doesn't seem to be locking....

    - by Rory
    I am playing with using flock, a bash command for file locks to prevent 2 different instances of the code from running more than once. I am using this testing code: ( ( flock -x 200 ; sleep 10 ; echo "original finished" ; ) 200>./test.lock ) & ( sleep 2 ; ( flock -x -w 2 200 ; echo "a finished" ) 200>./test.lock ) & I am running 2 subshells (backgrounded). The (flock NUM; ...) NUM>FILE syntax is from flock's man page. I expect that the first subshell will get an exclusive lock on test.lock, then wait 10 seconds, then print "original finished", all the time holding the lock. The second subshell will start at more or less the same time, wait 2 seconds, then try to get a lock on test.lock, but timeout after 2 seconds. If it gets a lock, then it'll print "a finished". If it doesn't get the lock, that subshell should stop, and nothing should be printed. Since the first subshell is waiting longer, it will keep the lock for 10 seconds, so the second subshell should not get the lock, and shouldn't finish. i.e. one should see "original finished" printed and not both. What actually happens is that "a finished" is printed, then "original finished" is printed. This implies that that the second subshell is either (a) not using the same lock as the first subhsell or (b) that it fails to get the lock, but continues to execute or (c) something else. Why don't those locks work?

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  • sed/awk or other: increment a number by 1 keeping spacing characters

    - by WizardOfOdds
    I've got a string: (notice the spacing) eh oh 37 and I want it to become: eh oh 36 (so I want to keep the spacing) Using awk I don't find how to do it, so far I have: echo "eh oh 37" | awk '$3>=0&&$3<=99 {$3--} {print}' But this gives: eh oh 36 (the spacing characters where lost, because the field separator is ' ') Is there a way to ask awk something like "print the output using the exact same field separators as the input had"? Then I tried with sed, but got stuck after this: echo "eh oh 37" | sed -e 's/\([0-9][0-9]\)/.../' Can I do arithmetic from sed using a reference to the matching digits and have the output not modify the number of spacing characters? Note that it's related to my question concerning Emacs and how to apply this to some (big) Emacs region (using a replace region with Emacs's shell-command-on-region) but it's not an identical question: this one is specifically about how to "keep spaces" when working with awk/sed/etc.

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  • Is Polyglot programming important?

    - by Kb
    Trying to learn more about Polyglot programming. What is it exactly and is it important? Look like it is cross platform coding and interoperability across platforms... I found this article by Ted Neward (Thoughtworks) interesting.

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  • Vim syntax highlighting: make region only match on one line

    - by sixtyfootersdude
    Hello I have defined a custom file type with these lines: syn region SubSubtitle start=+=+ end=+=+ highlight SubSubtitle ctermbg=black ctermfg=DarkGrey syn region Subtitle start=+==+ end=+==+ highlight Subtitle ctermbg=black ctermfg=DarkMagenta syn region Title start=+===+ end=+===+ highlight Title ctermbg=black ctermfg=yellow syn region MasterTitle start=+====+ end=+====+ highlight MasterTitle cterm=bold term=bold ctermbg=black ctermfg=LightBlue I enclose all of my headings in this kind of document like this: ==== Biggest Heading ==== // this will be bold and light blue ===Sub heading === // this will be yellow bla bla bla // this will be normally formatted However right now when ever I use an equals sign in my code it thinks that it is a title. Is there anyway that I can force a match to be only on one line?

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  • Keyboard input: how to separate keycodes received from user

    - by Iulian Serbanoiu
    Hello, I am writing an application involving user input from the keyboard. For doing it I use this way of reading the input: #include <stdio.h> #include <termios.h> #include <unistd.h> int mygetch( ) { struct termios oldt, newt; int ch; tcgetattr( STDIN_FILENO, &oldt ); newt = oldt; newt.c_lflag &= ~( ICANON | ECHO ); tcsetattr( STDIN_FILENO, TCSANOW, &newt ); ch = getchar(); tcsetattr( STDIN_FILENO, TCSANOW, &oldt ); return ch; } int main(void) { int c; do{ c = mygetch(); printf("%d\n",c); }while(c!='q'); return 0; } Everyting works fine for letters digits,tabs but when hiting DEL, LEFT, CTRL+LEFT, F8 (and others) I receive not one but 3,4,5 or even 6 characters. The question is: Is is possible to make a separation of these characters (to actually know that I only hit one key or key combination). What I would like is to have a function to return a single integer value for any type of input (letter, digit, F1-F12, DEl, PGUP, PGDOWN, CTRL+A, CTRL+ALT+A, ALT+LEFT, etc). Is this possible? I'm interested in an idea to to this, the language doesn't matter much, though I'd prefer perl or c. Thanks, Iulian

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  • Flashing window in gnu screen

    - by gotts
    I really like gnu screen but there is a problem in my environment when I use it. Examle: username@domain:/var/www$ l Display all 130 possibilities? (y or n) when you click [Tab] to perform autocompletion there is a screen flashing for a very short period of time(looks like white screen but I can see it for a very-very short time). There isn't any problems with that when I execute the same action in normal/non-screen environment. This is what my .screenrc looks like: attrcolor b ".I" termcapinfo xterm 'Co#256:AB=\E[48;5;%dm:AF=\E[38;5;%dm' defbce "on" term screen-256color-bce

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  • Write STDOUT & STDERR to a logfile, also write STDERR to screen

    - by Stefan Lasiewski
    I would like to run several commands, and capture all output to a logfile. I also want to print any errors to the screen (or optionally mail the output to someone). Here's an example. The following command will run three commands, and will write all output (STDOUT and STDERR) into a single logfile. { command1 && command2 && command3 ; } > logfile.log 2>&1 Here is what I want to do with the output of these commands: STDERR and STDOUT for all commands goes to a logfile, in case I need it later--- I usually won't look in here unless there are problems. Print STDERR to the screen (or optionally, pipe to /bin/mail), so that any error stands out and doesn't get ignored. It would be nice if the return codes were still usable, so that I could do some error handling. Maybe I want to send email if there was an error, like this: { command1 && command2 && command3 ; } logfile.log 2&1 || mailx -s "There was an error" [email protected] The problem I run into is that STDERR loses context during I/O redirection. A '2&1' will convert STDERR into STDOUT, and therefore I cannot view errors if I do 2 error.log Here are a couple juicier examples. Let's pretend that I am running some familiar build commands, but I don't want the entire build to stop just because of one error so I use the '--keep-going' flag. { ./configure && make --keep-going && make install ; } > build.log 2>&1 Or, here's a simple (And perhaps sloppy) build and deploy script, which will keep going in the event of an error. { ./configure && make --keep-going && make install && rsync -av --keep-going /foo devhost:/foo} > build-and-deploy.log 2>&1 I think what I want involves some sort of Bash I/O Redirection, but I can't figure this out.

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  • Why is the value of this string, in a bash script, being executing?

    - by Ross
    Hello Why is this script executing the string in the if statement: #!/bin/bash FILES="*" STRING='' for f in $FILES do if ["$STRING" = ""] then echo first STRING='hello' else STRING="$STRING hello" fi done echo $STRING when run it with sh script.sh outputs: first lesscd.sh: line 7: [hello: command not found lesscd.sh: line 7: [hello hello: command not found lesscd.sh: line 7: [hello hello hello: command not found lesscd.sh: line 7: [hello hello hello hello: command not found lesscd.sh: line 7: [hello hello hello hello hello: command not found hello hello hello hello hello hello p.s. first attempt at a shell script thanks

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  • Pulling a timestamp from an XML feed with PHP but seem to be to many digits

    - by Craig Ward
    I am pulling a timestamp from a feed and it gives 12 digits (1269088723811). When I convert it, it comes out as 1901-12-13 20:45:52, but if I put the timestamp into http://www.epochconverter.com/ it comes out as Sat, 20 Mar 2010 12:38:43 GMT, which is the correct time. epochconverter.com mentions that it maybe in milliseconds so I have amended the script to take care of it using $mil = $timestamp; $seconds = $mil / 1000; $date = date('Y-m-d H:i:s', date($seconds)); but it still converts the date wrong, 1970-01-25 20:31:23. What am I doing wrong?

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