Using harpoon vector symbol in LaTeX

My favorite vector symbol is a harpoon, but the harpoon package defaults to text mode, which will fail when math characters like \ell are used in the math mode.

To fix this, in your document header put:




will work.


Manually putting external USB drives into standby

You can manually put a USB HDD that doesn’t automatically spin-down after inactivity to sleep with the following command:

sg_start 0 --pc=3 /dev/sdc

where I assumed your HDD was at /dev/sdc. You can determine which /dev/sd* you’re at with the command

The HDD should automatically spring back to active spinning mode when you write a file to it, etc.

You can install the sg_start program via:
sudo apt-get install sg3-utils

The reason you might want to do this include that the HDDs put out some substantial heat when they’re not spun down. You don’t want to spin up/down too frequently (like every 5 minutes) but if you’re not using the drive for the night or a few days, it might be worthwhile to spin them down if heating is an issue.

Using Phoronix Test Suite 5

  1. Prerequisites
  2. sudo apt-get install php5-cli php5-curl php-fpdf

  3. install
  4. Download from, then type:
    sudo gdebi phoronix-test-suite_5*.deb

    if you don’t have gdebi, you can install gdebi on Ubuntu 14.04 by:

    sudo apt-get install gdebi-core

  5. run tests (from terminal)
  6. phoronix-test-suite benchmark c-ray
    phoronix-test-suite benchmark hpcc
    phoronix-test-suite benchmark scimark2
    phoronix-test-suite benchmark xonotic

  7. Listing all results on this PC
  8. phoronix-test-suite list-saved-results

  9. Converting results to PDF
  10. phoronix-test-suite result-file-to-pdf myTest

Matlab Compiler tbb.dll errors

Even with a fresh install of Windows 7 x64 and Matlab R2013b, I was getting tbb.dll related errors after compiling M-scripts using Matlab Compiler deploytool. The exe would compile, but upon running it would issue various tbb.dll errors.

This problem happened across multiple PCs. To fix this problem, I followed this process:

1) download latest Intel Threaded Building Blocks from:

extract them to c:\tbb
2) install Intel TBB by starting Command Prompt with Run As Adminstrator, then type
cd c:\tbb\tbb*\bin
tbbvars intel64 all

Then I went back to Matlab deploytool and recompiled.