mason

why you must use pinned transfers to compare CUDA device bandwidth

Mon, 18 Jan 2010 23:46:28 -0500

correct me if i'm wrong, but NVIDIA's bandwidthTest program included in the CUDA SDK takes single timing measurements and reports them. if there's any noise in the measurements, these single reports may be misleading. i wrote my own bandwidth test program that takes 100 measurements and spews out the resulting data for analysis. with my program at least, there is plenty of noise if you measure unpinned rather than pinned transfers.

notes on The Mythical Man Month

Tue, 09 Jun 2009 05:56:16 -0500

For tips on designing a software system, I read The Mythical Man-Month. I recommend it, but here are my notes in case you just want the juicy bits:

migrate from Google Docs to Evernote with gdocs2evernote

Thu, 08 Jan 2009 13:54:29 -0500

Google Docs and Evernote will both store your text data on their servers. I've used both for keeping my diary, but I'm moving over to Evernote completely now. Here's a python program I wrote that downloads all of your Google Docs from a particular folder and puts them into an Evernote notebook: gdocs2evernote.zip (Windows only)

do arithmetic on time with Timelab

Sun, 04 Jan 2009 10:55:23 -0500

A calculator that could do arithmetic on time, like 5:13*2 + 10:50 = 21:16, would be handy. So I built it. Download Timelab to try it! You'll need python to run Timelab (macs already have this installed).

Eigenfaces for art

Fri, 02 Jan 2009 12:27:07 -0500

If you discard color, a 100x100 pixel image has 10,000 pieces of information--one for each pixel. Consider each image a data point. To plot them, you'd need graph paper with 10,000 axes, because each pixel's value tells you the position of the image (data point) along the corresponding dimension. And you thought images were 2-D.

real-time seam carving with openFrameworks

Sat, 13 Dec 2008 17:01:28 -0500

As a final project for my computer graphics class last semester, I implemented a fast version of a technique called "seam carving". Seam carving resizes an image by removing the least noticeable bits. I designed my seam carver to do this resizing on video streaming in from a webcam in such a way that you could remove an object from the video. Read on for my writeup, or just download the code and try it for yourself.

How to solve "unknown error" when installing a device driver in Windows Vista

Tue, 28 Oct 2008 13:27:17 -0500

Windows Update kept trying to upgrade my graphics card (Intel 945GM in Lenovo X60 tablet) and failing. I tried manually upgrading the driver with ones from both Intel and Lenovo, and neither worked. Here are the steps that solved my problem:

Random grammatical sentence generator using CFG

Sat, 18 Oct 2008 01:47:09 -0500

Context-free grammars (CFGs) can be used as a model for natural language. That means they capture the structure of language in a relatively simple form that can be reasoned about and used to generate new instances of natural language. My natural language processing book says CFGs were proven insufficient for modeling German spoken in Zurich (Speech and Language Processing (2nd Edition), p.538), but they're good enough to bring you the following silly, random, grammatical sentences:

Is the Problem of Other Minds a problem?

Sat, 27 Sep 2008 12:37:51 -0500

The Book of Tea contains an excerpt I love:

One day Soshi was walking on the bank of a river with a friend. "How delightfully the fishes are enjoying themselves in the water!" exclaimed Soshi. His friend spake to him thus: "You are not a fish; how do you know that the fishes are enjoying themselves?" "You are not myself," returned Soshi; "how do you know that I do not know that the fishes are enjoying themselves?"

Find yourself in photos of the SF Marathon (more coming soon)

Thu, 11 Sep 2008 11:10:57 -0500

I ran the half-marathon in San Francisco this past summer. It was amazing. Afterwards I wanted pictures to remember it by--specifically, pictures that had me in them to remember my experience. Before the race, MarathonFoto informed me that "you and your family will not have to worry about trying to capture your special race moments" because they would take pictures. Great! They neglected to mention those pictures would cost $40 each to download.

I liked the pictures, but that heads-up they gave before the race was slimy. I wondered, "how can I make a better, cheaper service for finding photos of myself (and put these guys out of business :P)?" The result is bibfind.com: a crowd-sourced photo tagging system that uses the bib numbers worn by runners to identify them in photos.

Automatic style-checking with Strunk and White's rules

Fri, 05 Sep 2008 13:15:49 -0500

I read The Elements of Style by Strunk and White to get better at writing. The biggest section is on common misuses of words and expressions in English. I thought the section was valuable, but more than I'd be able to keep in my head while writing. To solve that problem, I made a script that analyzes some given text and then annotates each potential misuse with a link to Strunk's guidance.

Making whitespace meaningful in order of operations

Fri, 29 Aug 2008 23:23:06 -0500

Of all the mundane details that programming bothers me with, operator precedence/arithmetical order of operations pisses me off the most. Pardon the vulgarity, but if you've ever had to wonder whether 5 + 6 * 2 was equal to 22 or 17, or even worse--had a bug caused by guessing wrong in that sort of situation, you know how I feel.

Spatial Frequency in Vision and (a bit about) Art

Fri, 15 Aug 2008 17:19:44 -0500

I just gave a presentation in my Cognitive Neuroscience course at Stanford about Oliva and Schyns' paper "Coarse Blobs or Fine Edges? Evidence That Information Diagnosticity Changes the Perception of Complex Visual Stimuli", doi:10.1006/cogp.1997.0667. I was happy with the presentation, so I post my slides here for anyone who's interested.

iphone call data visualization

Thu, 31 Jul 2008 00:54:40 -0500

I read Edward Tufte's book The Visual Display of Quantitative Information, and afterwards I was burning to visualize some data. I settled on charting the time of day that I make phone calls at.

WANTED: Engineer to make wildest fantasies reality

Mon, 07 Jul 2008 13:33:35 -0500

As a software engineer with experience doing web development, I hear a lot of people with ideas for hot new websites. In most of these situations where there's an idea looking for someone to implement it, I get the sense that the software engineer's point of view isn't understood. Here's my edited response to a request for someone with spare time to implement an idea that was described at the level of detail of requiring community features and that users be able to upload content: