Error Writing Pipe Matlab
toolboxes, and other File Exchange content using Add-On Explorer in MATLAB. » Watch video Highlights from popen read and write Popen access from Matlab View all files Join the 15-year community celebration. Play games and win prizes! » Learn more 4.66667 4.7 | 3 ratings Rate this file 14 Downloads (last 30 days) File Size: 112 KB File ID: #13851 Version: 1.0 popen read and write by Dan Ellis Dan Ellis (view profile) 15 files 257 downloads 4.77232 04 Feb 2007 (Updated 05 Feb 2007) MEX source to acccess popen r/w | Watch this File File Information Description popen() -- for "pipe open" -- is a very useful system call provided in many flavors of Unix. It runs a command passed in as a string then returns a file handle so that the parent process can read or write to the process as if it was a file; data passed this way is connected to the standard input or the standard output of the child process. I created this because I wanted to process very long MP3 files in Matlab. Originally I wrote mp3read to allow me to decode just a small section of a long MP3 file without having to decode the whole thing, but every time I wanted to read another segment, I had to open the file again, then seek through to the point I wanted to read. Instead, by using popen to open an MP3 decoding process that writes to standard output, I can "pull" as many frames as I want from the file, then put the process to sleep while I deal with those frames, then, on my next read from popen, the process is reawoken and the next block of data can be accessed. But this could be used for any application where there are long data streams to read or write, and you want to handle them a bit at a time. Two functions are provided, popenr.c for reading from command pipes, and popenw.w for writing to command pipes. Reading and writing to the same command is not supported at present. MATLAB release MATLAB 7.3 (R2006b) Other requirements Requires popen() in underlying platform i.e. some kind of Unix (Linux, Mac OS X, ...) Tags for This File Please login to tag files. data exportdata importmexopenpipepopensourceunix Cancel Please login to add a comment or
Support Answers MathWorks Search MathWorks.com MathWorks Answers Support MATLAB Answers™ MATLAB Central Community Home MATLAB Answers File Exchange Cody Blogs Newsreader Link Exchange ThingSpeak Anniversary Home Ask Answer Browse More Contributors Recent Activity Flagged Content Flagged as Spam Help MATLAB Central Community Home MATLAB Answers File Exchange Cody Blogs Newsreader Link Exchange ThingSpeak Anniversary Home Ask Answer Browse More Contributors Recent Activity Flagged Content Flagged as Spam Help Trial software Kelly Kearney (view profile) 12 questions 479 answers 237 accepted answers Reputation: 1,422 Vote1 Increase limit on number https://www.mathworks.com/matlabcentral/fileexchange/13851-popen-read-and-write of open files Asked by Kelly Kearney Kelly Kearney (view profile) 12 questions 479 answers 237 accepted answers Reputation: 1,422 on 3 Jul 2014 Latest activity Commented on by Kelly Kearney Kelly Kearney (view profile) 12 questions 479 answers 237 accepted answers Reputation: 1,422 on 9 Jul 2014 44 views (last 30 days) 44 views (last 30 days) Short question(s):Is there a https://www.mathworks.com/matlabcentral/answers/140165-increase-limit-on-number-of-open-files way to increase the maximum number of open files allowed at a given time?For that matter, what exactly sets this limit? Matlab, or the OS? This answer seems to imply that it's the latter; however, I seem to be hitting the limit around 590 files, while my OS says it can handle 1024:>> system('ulimit -a') core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited file size (blocks, -f) unlimited max locked memory (kbytes, -l) unlimited max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 1 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 709 virtual memory (kbytes, -v) unlimited Longer explanation:I know the short answer to this question is "Why on earth would you keep that many files open at once? Rewrite your program to not do that!" So here's the long explanation... I'm open to suggestions, but I'm really trying to avoid a complete overhaul of the code.I'm running a model that integrates a system of ODEs forward in time. As it runs, output is saved t
Support Answers MathWorks Search MathWorks.com MathWorks Answers Support MATLAB Answers™ MATLAB Central Community Home MATLAB Answers File Exchange Cody Blogs Newsreader Link Exchange ThingSpeak Anniversary Home Ask Answer https://www.mathworks.com/matlabcentral/answers/294266-i-am-writing-a-code-that-keep-giving-error-message Browse More Contributors Recent Activity Flagged Content Flagged as Spam Help MATLAB Central Community Home MATLAB Answers File Exchange Cody Blogs Newsreader Link Exchange ThingSpeak Anniversary Home Ask Answer Browse More Contributors Recent Activity Flagged Content Flagged as Spam Help Trial software PaulBan (view profile) 2 questions 0 answers 0 accepted answers Reputation: 0 Vote0 I am writing a code that keep giving error writing error message. Asked by PaulBan PaulBan (view profile) 2 questions 0 answers 0 accepted answers Reputation: 0 on 8 Jul 2016 Latest activity Commented on by PaulBan PaulBan (view profile) 2 questions 0 answers 0 accepted answers Reputation: 0 on 8 Jul 2016 1 view (last 30 days) 1 view (last 30 days) function f=DarcyFricFact(D,E,Re) % Calculatre Friction factor % f: is friction error writing pipe % E :pipe roughness (for cast iron, 0.010") % D: pipe diameter in inches % Re: Reynolds number % For loop will help use to write the program %%%%%% Argument D=[2 5 10]; Re=(4000:400000); E=0.01; f1=zeros(1,350000); f2=zeros(1,350000); f3=zeros(1,350000); n=1 Num=length (Re); k=1; f=zeros(k,Num); for n=1:Num; a = 2/log(10) b = (E./D)/3.7; d=log(10)*Re(n)/5.02 s=b*d+log(d); q=s.^(s/(s+1)); g=b*d+log(d./q); z=log(q/g); DLA=z*(g/(g+1)); DCFA=DLA.*(1+(z/2)/((g+10.^(2) + (z/3).*(2.*g-1)))); f(k)=(a*((log(d/q)+DCFA))).^(-2); end end 2 Comments Show all comments per isakson per isakson (view profile) 33 questions 1,476 answers 669 accepted answers Reputation: 3,899 on 8 Jul 2016 Direct link to this comment: https://www.mathworks.com/matlabcentral/answers/294266#comment_378043 There are many problems. ReplacingDCFA=DLA.*(1+(z/2)/((g+10.^(2) + (z/3).*(2.*g-1)))); byDCFA=DLA.*(1+(z/2)./((g+10.^(2) + (z/3).*(2.*g-1)))); fixes the first. See Debug a MATLAB Program PaulBan PaulBan (view profile) 2 questions 0 answers 0 accepted answers Reputation: 0 on 8 Jul 2016 Direct link to this comment: https://www.mathworks.com/matlabcentral/answers/294266#comment_378046 Thanks Tags please any help Products No products are associated with this question. Related Content 0 Answers Log In to answer or comment on this question. Related Content Join the 15-year community celebration. Play games and win prizes! Learn more MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi Learn more Discover what