• Research - miscellaneous

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    November 21, 2011 | Posted by Suayb S. Arslan

  • 1) I want to start off with a frequent problem related to linux compilation issues that you may end up geting stuck when executing a file (ubuntu 12.04 and above - albeit your compilation shall work just fine). It is known as "error while loading shared libraries. cannot open shared object file: No such file or directory". In a number forms i find that people talk about changing either /etc/ld.so.conf file or /etc/ld.so.conf.d/*.conf files (by creating of their own like .../local.conf etc). However, none worked for me. One of the neat solutions is "sudo /sbin/ldconfig -v". The following explanation (which i very much like bytheway) is due to Mr. Prakash...

  • "ldconfig creates the necessary links and cache to the most recent shared libraries found in the directories specified on the command line, in the file/etc/ld.so.conf, and in the trusted directories (/lib and /usr/lib). The cache is used by the run-time linker, ld.so or ld-linux.so. ldconfig checks the header and filenames of the libraries it encounters when determining which versions should have their links updated"

Another way of doing it is to specify the search path at the time of reconfiguration: "./configure LD_LIBRARY_PATH=/usr/local/lib". Eitherway, you should be able to execute your *.sh files.

2) I have been working with reliability engineering, durability and availabulity estimations of storage systems for a while and the cumulative distribution function (cdf) of Binomial Density is something I have been using over and over again. On many occations, I have used Matlab and python to calculate the cdf for some corner cases in which the probability expressions become imprecise in cases of 0^Inf and Inf^0. For those case, I have realized that it is convenient to use incomplete beta function to accurate approximate the CDF. Here is the document I have been using while doing research on Tape reliability @ Quantum Corp., 2013.

3) Let us assume you used LaTeX (or word) to create an IEEE conference paper. If the submission is done over EDAS, or your paper went through the inspection and got accepted and you are asked to upload the final version of your paper to IEEE Xplore. Yet, during this process you faced a weird problem: "Not all fonts are embedded inside the pdf document". Well this may happen when the pdf generator does not use the system fonts but manually points fonts or you used an external program to generate figures, tables that has different font characteristics or encoding.

IEEE provides a nice tool called "xpress plus" that requests a compressed file in which you include the DVI as well as the source files (tex+figures etc) and generates Xplore(EDAS)-compatible pdf file with all the fonts embedded. However, this tool requires you to have a valid and non-expired conference ID for login. Plus, even if you have it, sometime it crashes and sends a failure notification and lets the sysadmin to know about it. Hardworking IEEE guys will probably get back to you in 24 hours at the latest with the compatible pdf attached to the return email.

There are also solutions on web based on the assumption that you have a paid Adobe Acrobat version where you can use print pdf feature with few configuration details to generate compatible pdf document generation.

Despite all that, I have found an immediate solution for LaTeX users. For whatever editor you use, first generate an appropriate your_file.ps (postscript file). The use ps2pdf function to generate the pdf using the following options. (First navigate to the location (directory) of your_file.ps file)

Windows: ps2pdf -dPDFSETTINGS#/prepress -dEmbedAllFonts#true -dMaxSubsetPct#100 -dCompatibilityLevel#1.3 your_file.ps your_file_output.pdf

For Linux users, just replace "#" with "=" in the above command phrase. It just should work.

4) When you use document differecing software (for instance linux's diff or sdiff or even meld with a gui support), even with --ignore-all-spaces option, tabs will be compared and found different if your editor replaces tab characters with spaces. So I would recommend that you make sure that your editor uses the actual tab character. Apart from differencing operation, there are also other use cases where tab-ing is important. For instance make requires tab characters in Makefiles for a compatible run. Here is how you can change tab-ing from spacing to actual tab character in gedit:
> gsettings set org.gnome.gedit.preferences.editor insert-spaces false

5) I am sometimes asked about what unix/linux OS platform to use for carrying out projects, homeworks etc. I'd recommend RedHat's EL if you have money. If not, choose centos 7 or later for a good set of important reasons. Ubuntu/Debian/Fedora are not too bad and good for evaluation pruposes. It is completely a personal choice of mine but as the time of writing this, RHEL or Centos 7 supports the following and which Ubuntu/Debian do not:

>> Being able to create a single partition of capacity greater 2TB (using say fdisk utility with gpt disk labeling).

>> ... More to come later.

6) One of the well known Erasure code package is Jerasure (although the latest version 2.0 is reported to be associated with patent infringement issues and removed from the site - I personally think that Dr. Plank and his fellow friends should still make it open source for academia) by Dr. Plank and his colloborators. Here i will note (soon) some of the bugs/issues and recommendations (about version 2.0) for future releases of this package - if it ever gets through after StreamScale's interception!... I may also report some performance related metrics regarding the codes covered in this package and their competitors.

  • 7) I was also experimenting with Ceph Jerasure plugin and LRC plugin on a real cluster at Quantum (now at MEF University). The performance on a real system might potentially be quite different than the isolated simulation performance of Jerasure package. Will post some results some time soon.

8) Latex is the word processor being used by research community. So here is the excellent Short Math Guide for LATEX by Michael Downes - American Mathematical Society.

  • Here a solution for black screen of death, usually encountered in computers run by Vista OS. BTW, in case of urgent need: *see MICROSOFT BOYCOTT! web site! :))

    One of the respectable institutions around USA, of which i am a member and in which a serious science going on, is Simply Sigma Xi. Here is the American Scientist!

    IEEE Gamesman problems:

    • Published on Sept./Oct. 2008 IEEE potentials Issue: here!

    Here I have some stuff related to my internships:

    • Synthetic Video sequences for Testing: (@MERL): Download here! (RAR file) .