Dot Matrix Average of Dots - John Dunn, Consultant, Ambertec, P.E., P.C.

The frequency of usage of letters in a six-hundred word essay was used to estimate the average power dissipation of an alpha-numeric, 7 x 5 dot matrix display using LEDs.

Each letter has some particular number of dots turned on. The letter "A" for example, activates seventeen dots. Then from the essay, each letter was found to have some frequency of usage which again, for the commonly used letter "E", was 13.54%, but for the rarely used letter "Q", was only 0.03%.

The average usage in ordinary text turned out to be of 15.6 dots per character.      

I repeated this excercise using O'Henry's short story "Man About Town", perhaps my favorite of his works, and then again on an essay about Andrew Jackson in the thought that the repeated appearance of the name "Jackson" with the letter "J" might skew the result.

The end value of average usage didn't change. This seems to be pretty much the end result.

 

Comments

[Jim Anderson]

Wikipedia at http://en.wikipedia.org/wiki/Letter_frequency discusses this topic and points out that the frequencies vary with the language, the author, and the topic. For example articles on Queens (Q), X-rays (X) and Zebras (Z) would have distorted frequency distributions.

[DonH]

I hated probability and statistics in school.
But this is interesting.
Isn't there something like making a
control set to remove the over weight of certain letters.
Like one fullheaded man in a room full of
bald ones?

[William Ketel]

I guess that I had never thought about finding the average power dissipation in a 5x7 display, although we did do an evaluation of the display errors produced by single-segment failures in a lamp-type seven segment display. That was prior to the availability of reliable LED devices. The result was some rather elaborate display driving circuits that verified that each segment was drawing enough current. Then along came LEDs and saved the day, since a redundant display was simple to implement, and much cheaper than having seven monitor circuits.