July 20, 2012 — Michael Trott, Chief Scientist

*(This is the first post in a three-part series about electrostatic and magnetostatic problems involving sharp edges.)*

*Mathematica* can do a lot of different computations. Easy and complicated ones, numeric and symbolic ones, applied and theoretical ones, small and large ones. All by carrying out a *Mathematica* program.

Wolfram|Alpha too carries out a lot of computations (actually, tens of millions every day), all specified through free-form inputs, not *Mathematica* programs. Wolfram|Alpha is heavily based on *Mathematica*, and many of the mathematical calculations that Wolfram|Alpha carries out rely on the mathematical power of *Mathematica*. And while Wolfram|Alpha can carry out a vast amount of calculations, it cannot carry out all possible calculations, either because it does not (yet) know how to do a calculation or because the (underlying *Mathematica*) calculation would take a longer time than available through Wolfram|Alpha. So for a detailed investigation of a more complicated engineering, physics, or chemistry problem, having a copy of *Mathematica* handy is mandatory.

But there is also the reverse relation between *Mathematica* and Wolfram|Alpha: Wolfram|Alpha’s knowledge, especially its data knowledge, allows it to carry out investigations and calculations that can substantially increase the power of pure *Mathematica*. And all of this is because Wolfram|Alpha’s knowledge is accessible through the `WolframAlpha[]` function within *Mathematica*.

March 14, 2012 — Jackie Tran, computerbasedmath.org

In the “Society’s Changing Needs for Math” session at the The Computer-Based Math (CBM) Education Summit 2011, Marcus du Sautoy, Paul Wilmott, Charles Fadel, and Tim Oates discussed their views in one of the summit’s key sessions.

There was a lot of energy for debate from our summit attendees, and we did not have the time to expand on every topic after each talk. Hopefully these bite-sized videos from our speakers will open up discussions to all. Have your say and leave your thoughts on the comment section of this post or on Computer-Based Math’s YouTube Channel.

October 26, 2011 — Samuel Chen, Technical Communication & Strategy

What do computer animation, oil exploration, and the FBI’s database of 30 million fingerprints have in common?

Wavelet analysis.

As of Version 8, wavelet analysis is an integral part of *Mathematica*.

Wavelets themselves are short-lived wave-like oscillations. Taking the Morlet wavelet, for example, we can see that unlike sines and cosines, this wave-like oscillation is localized in the sense that it does not stretch out to infinity.

January 26, 2011 — Jon McLoone, International Business & Strategic Development

*Mathematica* can make you feel like a computational superman. Armed with that attitude and some schoolboy knowledge of cryptography, I turned my attention to cipher breaking this week, only to discover buried kryptonite.

The weakness of ciphers (where you swap every occurrence of a particular letter in your message with the same different letter) is that they don’t change the patterns of letters. The simplest attack that exploits this fact is frequency analysis. The most common letter in English is “e”, and so it follows that the most common character in an encoded message (assuming the message is written in English) will correspond to “e”. And so on through the alphabet.

Mary Queen of Scots famously lost her head when Queen Elizabeth’s spymaster broke Mary’s cipher using frequency analysis. I figured that if sixteenth century spies could do it by hand, I should be able to automate it in *Mathematica* in about 10 minutes.

December 9, 2010 — Jon McLoone, International Business & Strategic Development

I just published a *Mathematica* package that provides an alternative, richer implementation of units and dimensional analysis than the built-in units package. You can get it here. Aside from being a really nice extension to *Mathematica*, it is also an interesting case study in adding a custom data “type” to *Mathematica* and extending the knowledge of the built-in functions to handle the new “type”.

First I have to explain the point by answering the question, “What’s wrong with the built-in units package?” Well, there is nothing actually wrong with it, it just doesn’t apply *Mathematica*‘s automation principles. It can convert between several hundred units and warn if a requested conversion is dimensionally inconsistent. But give it an input like…

and it does nothing with it until you specify that you want the result in a specific unit. The core reason is that it doesn’t teach the system, as a whole, anything about units, or even that the symbol “`Meter`” is any different than the symbol “x”. All of the knowledge about units and `Meter` in particular is contained in the `Convert` command.

November 30, 2010 — Ed Pegg Jr, Editor, Wolfram Demonstrations Project

Let’s flip a coin, over and over. Beforehand, the players each pick a sequence of flips. The sequence that occurs first wins. With HH vs. TH, HH will win if the first two flips are HH and will lose if any of those flips are tails. HH vs. TH has a 1/4 vs. 3/4 possibility of winning.

Phrased a different way: Suppose I offer a bet on a series of coin flips. One of these bets would be bad for you. Which one? The odds of the event occurring are given at the end. (The second bet is the bad bet to take.)

HTT appears before TTT. If it does, I give you $1. If not, you give me $4. (7/8)

HHT appears before TTT. If it does, I give you $1. If not, you give me $3. (7/10)

THH appears before HHT. If it does, I give you $1. If not, you give me $2. (3/4)

HTH appears before THH. If it does, I give you $1. If not, you give me $1. (1/2)

This is the strange world of Penney’s game. Here is a table of odds and facts for various 3-flip games. Calculating these odds can be both tedious and mathematically demanding—a natural job for *Mathematica* or *Mathematica Home Edition*.

October 1, 2010 — Jon McLoone, International Business & Strategic Development

Buried deep in the list of new technology in the *Mathematica* development pipeline was the item “integration of oscillatory functions (univariate, multivariate)—new algorithm”. I expect most people will overlook it, as I did, in favor of the new functions, new directions, big infrastructure, and the eye candy. Even worse, most people who will use it won’t even know—it will be selected automatically when needed, like many of *Mathematica*‘s algorithms. So I think it’s my duty to share my discovery that this algorithm is actually really cool.

Why is it so cool?

The first clue I had was when I read in the notes that this was the first time anyone had fully automated the algorithm into a very wide class of problems. Second, that it was a hybrid numeric-symbolic method (putting it beyond the reach of most numerical systems). And finally, that it was developed by the talented Wolfram Research developer Andrew Moylan.

September 27, 2010 — Jon McLoone, International Business & Strategic Development

Since I just heard that the video for Conrad Wolfram’s recent TED talk “Stop teaching calculating, start teaching math” will be coming out soon, I thought I would address the single biggest fear that I hear when I talk about using computers in math education.

The objection that using computers will “dumb down” education comes with the related ideas “students have to learn to do it by hand or how will they know they have got the right answer”, “they won’t understand what is happening unless they do it themselves”, and so on.

Well, let’s examine this by looking at a typical math question that I know I had to solve at some point in my education.

August 30, 2010 — Ed Pegg Jr, Editor, Wolfram Demonstrations Project

Back in 325 BC, Aristotle talked about which polyhedra can fill space, and noted that regular tetrahedra could fill space.

Around 1470 AD, Regiomontanus showed that Aristotle was wrong. He also found the spot where a statue on a pedestal appears the largest, as shown in the Demonstration “The Statue of Regiomontanus”.

In 1896, Minkowski tried to solve the problem of how well tetrahedra could pack. He failed. But he did introduce many valuable tools to math, such as “The Minkowski Sum of Two Triangles”.

In 1900, Hilbert tried the problem of tetrahedra packing and included it as a part of problem 18 in his list of unsolved problems. Hilbert is also famous for the Hilbert curve and “The Hilbert Hotel”.

July 13, 2010 — Ed Pegg Jr, Editor, Wolfram Demonstrations Project

Is it possible to have a pair of nonstandard dice with the same odds as regular dice?

Sure. You just need to know how to calculate the odds, and how to determine what different numbers could be on the faces to give the same odds. Let’s start with some tables.

The addition table is one of the first tables learned in school. Here is

one way to present an addition table in *Mathematica*.