Running Calculus on an Arduino

It was Stardate 2267. A mysterious life form known as Redjac possessed the computer system of the USS Enterprise. Being well versed in both computer operations and mathematics, [Spock] instructed the computer to compute pi to the last digit. “…the value of pi is a transcendental figure without resolution” he would say. The task of computing pi presents to the computer an infinite process. The computer would have to work on the task forever, eventually forcing the Redjac out.

Calculus relies on infinite processes. And the Arduino is a (single thread) computer. So the idea of zeno_03running a calculus function on an Arduino presents a seemingly impossible scenario. In this article, we’re going to explore the idea of using derivative like techniques with a microcontroller. Let us be reminded that the derivative provides an instantaneous rate of change. Getting an instantaneous rate of change when the function is known is easy. However, when you’re working with a microcontroller and varying analog data without a known function, it’s not so easy. Our goal will be to get an average rate of change of the data. And since a microcontroller is many orders of magnitude faster than the rate of change of the incoming data, we can calculate the average rate of change over very small time intervals. Our work will be based on the fact that the average rate of change and instantaneous rate of change are the same over short time intervals.

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Blackberry download limit remover

On the standard Blackberry Web Browser, there is a fixed file download limit of 2.3MB. Many users avoid this by installing a 3rd party browser (such as Opera Mini, for example), but there is still that bitter taste for having an extra web browser around just to download decently sized files. This limit seems to be imposed by a certain WAP port that the Blackberry is set to use by default, which blocks any file greater than this. Fortunately, [0mie] has found a way to reconfigure the default Blackberry Browser to use a different port without this restriction. Step by step walk through, links to the file required, and screen shots of large file downloads are provided. [0mie] claims that this hack works on a number of different phones and OS versions, and we are sure he would appreciate a wider audience to test this with.

[Note: This hack seems to use a Chinese provider as a proxy, so there may be privacy issues, etc. As always, hack at your own risk.]