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The Wolfram Demonstrations Project Goes 7

Just a couple of weeks ago we released Mathematica 7. This week we’ve made the Wolfram Demonstrations Project live with Mathematica 7. All the 4270 Demonstrations on the site run with Mathematica 7 (yes, we tested every single one of them, partly automatically, partly by hand). And we added 147 new Demonstrations that specifically make use of Mathematica 7’s features. Most of those Demonstrations were created internally within Wolfram Research, in a small frenzy of activity right around the actual release of Mathematica 7. I was involved in organizing this Demonstrations-fest. It’s very impressive how quickly it’s possible to create so much high-quality material with Mathematica. Of course, it helped that we were able to work directly with the key developers of much of Mathematica 7’s functionality—so people were often creating Demonstrations based on the very features they had implemented in the system. The new image processing system in Mathematica 7 was a particularly fertile source of Demonstrations. Charting, splines and vector visualization are other areas that have spawned all sorts of interesting Demonstrations. Here are a few of my personal favorites:
Design & Visualization

The Incredible Convenience of Mathematica Image Processing

It’s been possible since Version 6 of Mathematica to embed images directly into lines of code, allowing such stupid code tricks as expanding a polynomial of plots. But is this really good for anything? As with many extremely nifty technologies, this feature of Mathematica had to wait a while before the killer app for it was discovered. And that killer app is image processing. Mathematica 7 adds a suite of image processing functions from trivial to highly sophisticated. To apply them to images, you don’t need to use any form of import command or file name references. Just type the command you want to use, then drag and drop the image from your desktop or browser right into the input line.
Announcements & Events

Surprise! Mathematica 7.0 Released Today!

In the middle of last year, we finished our decade-long project to reinvent Mathematica, and we released Mathematica 6. We introduced a great many highly visible innovations in Mathematica 6—like dynamic interactivity and computable data. But we were also building a quite unprecedented platform for developing software. And even long before Mathematica 6 was released, we […]

Computation & Analysis

Visualizing Integrals

Calculus II is one of my favorite classes to teach, and the course I’ve probably taught more than any other. One reason for its special place in my heart is that it begins on the first day of class with a straightforward, easily stated, yet mathematically rich question: what is the area of a curved region? Triangles and rectangles—figures with straight sides—have simple area formulas whose derivation is clear. More complicated polygons can be carved up into pieces that are triangles and rectangles. But how does one go about finding the area of a blob?

After simplifying the blob to be a rectangle whose top side has been replaced with a curve, the stage is set for one of the classic constructions in calculus. The area of our simplified blob, reinterpreted as the area under the graph of a function is approximated using a series of rectangles. The approximation is obtained by partitioning the x axis, thus slicing the region into narrow strips, then approximating each strip with a rectangle and summing all the resulting approximations to produce a Riemann sum. Taking a limit of this process by using more and narrower rectangles produces the Riemann integral that forms the centerpiece of Calculus II. Several Demonstrations from the Wolfram Demonstrations Project, including "Riemann Sums" by Ed Pegg Jr, "Common Methods of Estimating the Area under a Curve" by Scott Liao and "Riemann Sums: A Simple Illustration" by Phil Ramsden show that this construction and images like the one below from "Riemann Sums" are part of the iconography of calculus.
Best of Blog

Stock Market Returns by Presidential Party

The New York Times recently published an “Op-Chart” by Tommy McCall on its Opinion page showing what your returns would have been had you started with $10,000 in 1929 and invested it in the stock market, but only during the administrations of either Democratic or Republican presidents. His calculations showed that if you had invested only during Republican administrations you would now have $11,733 while if you had invested only during Democratic administrations you would now have $300,671. Twenty-five times as much!

That’s a pretty dramatic difference, but does it stand up to a closer look? Is it even mathematically plausible that you could have essentially no return on your investment at all over nearly 80 years, just by choosing to invest only during Republican administrations?

To answer these questions, I of course turned to Mathematica.

And the answer is that yes, it is mathematically plausible, using the assumptions made by McCall. My analysis using historical Dow Jones Industrial Average data available in Mathematica’s FinancialData function roughly matches the figures in the Times, which used Standard & Poor’s data. (I used the Dow because it’s more convenient, not because I think it’s a better measure.)

But the fact that they are correct doesn’t mean the figures are even remotely meaningful. Here are some problems with the New York Times’ Op-Chart:
Announcements & Events

Russell Towle: 1949–2008

A few times a year they would arrive. Email dispatches from an adventurous explorer in the world of geometry. Sometimes with subject lines like “Phenomenal discoveries!!!” Usually with images attached. And stories of how Russell Towle had just used Mathematica to discover yet another strange and wonderful geometrical object. Then, this August, another email arrived, […]

Computation & Analysis

Analyzing US 2008 Elections with Mathematica

The 2008 United States presidential election is arguably the most interesting US presidential election in my lifetime.

Already, millions of Americans have registered to vote for the first time in their lives.

Regardless of the outcome, America is going to elect either its first black president or its first female vice president.

America will elect a sitting US senator to the highest office in the land—which, until now, has only occurred twice in US history (Warren Harding and John F. Kennedy were US senators).

Both presidential candidates were born outside of the continental United States.

If elected, John McCain will be the oldest sitting US president upon ascension to the presidency.

Never before in US history has there been such a large disparity in age between the two presidential candidates, either.

It’s also the first election you can analyze using Mathematica 6.
Education & Academic

Seeing beyond a Theorem

Mathematics is a notoriously technical subject that prizes exactingly precise statements. The square of the hypotenuse of a right triangle is the sum of the squares of the legs, not the sum of their cubes, nor the difference of their squares. Such precision produces the clarity that makes the subject so powerful, but occasionally it comes at the cost of easy understanding. Indeed, more-complicated mathematical statements often sound bewildering upon first reading. Take the following theorem in plane geometry (deep breath...):

Let ABC be a triangle. Let DEF be parallel to AC with D on AB and E on BC. Let FGH be parallel to AB with G on BC and H on AC. Let r, r1, r2 and r3 be the radii of the incircles O, O1, O2 and O3 of the triangles ABC, DBE, EFG and HGC, respectively. If F is outside of ABC, then r = r1 + r2 + r3. Got it? Many theorems of mathematics, including this one, are easier to communicate by picture than by words. Here’s the scenario described in the theorem (images in this post are produced by slightly modified versions of the code for the Demonstration “The Radii of Four Incircles,” which is one of nearly 200 Demonstrations about theorems in plane geometry written by Jay Warendorff for the Wolfram Demonstrations Project):
Announcements & Events

Going Wordless at the Advanced Mathematica Summer School

No, not a vow of silence, but rather, some suggestions about how to move documents from Microsoft Word into Mathematica. A number of us Wolfram Research staffers contributed to our recent Summer School effort by sharing mentoring duties. In my case I worked with Richard Werthamer, a physicist who is publishing a book on the science of casino gambling strategies. His project includes programs verifying his research, and he’s eager to translate them into Mathematica in order to exploit all the new dynamics and plotting features of Version 6. At the same time, he quite naturally wants to move his existing manuscript into Mathematica notebook form to deliver a computable document, combining text and interactive Mathematica content distributable on the Mathematica Player platform. Richard’s situation is pretty common. He prepared his manuscript with MS Word, and a great new feature delivered in Mathematica 6.0.3 allows for the exchange of MathML on the clipboard with MS Word 2007 straight “out of the box”. In other words, after creating a formula in Word using its new native math typesetting system, simply select the formula, copy, then switch to Mathematica to paste into a notebook.