Lots of good stuff in +Plus Magazine #50

As usual, much good math to read about in this issue of Plus. My favorites:

Music from sine waves

A new approach to solving fluid dynamics problems.

Sundaram's sieve for prime numbers.

And just for you, Queen Anne, way too much geometry.

New Dumas novel (mostly) discovered

This old Guardian article from May 2008 talks with Claude Schopp, a Dumas scholar who turned up most of an unknown Dumas novel.

"Imagine that a previously unknown Dickens novel suddenly turned up after gathering dust for more than 130 years. The mere suggestion seems ridiculous. How could a book by one of Britain's best-known 19th-century writers possibly have slipped through the net for so long? Or even at all? Yet that is precisely what happened to Alexandre Dumas's final epic, Le Chevalier de Sainte-Hermine, which was published for the first time in France three years ago and is being published in English this week as The Last Cavalier."

Time lapse Friday

Baby plays on the floor
Gecko eaten by ants
Assembly of the Jaguar supercomputer
Mushroom growth
Butterfly pupates, emerges
An entire football game in 1:43 (best part: the marching bands)
Baby eating strawberry

Friday floobydust

PC Magazine's best free software for 2009

CNET news story about the 1984 Apple Superbowl commercial

A very thorough online calculator from Casio, with arbitrary precision, lots of special functions and application libraries

Wednesday flooby

A stunning lenticular cloud over New Zealand

How tube amps really work (scroll down for the photgraph)

Stanley Fish and the value of humanities

Faster numeric arc lengths on the Voyage 200 and TI-89

The built-in arclen() function will return a numeric result for an arc length if a symbolic solution cannot be found. For example,

arclen(-x^3 + 3*x^2 - 2x + 2/x - 2/x^2 + 1, x, .769, 2.428)

returns 4.2413 in about 62 seconds in APPROX mode. We can speed this up by using nint() to numerically integrate the arc length integrand, as follows.

First define a simple function to find the arc length integrand:

: arcleni(f,x)
: Func
: sqrt((d(f,x))^2+1)
: EndFunc

where f is the function of the desired arc length and x is the independent variable. d() is the built-in derivative function. We then find the arc length with

nint(arcleni(-x^3+3*x^2-2x+2/x-2/x^2+1,x),x,.769,2.428)

which returns the arc length in about 27 seconds, saving 35 seconds.

It is likely that arclen() spends the extra time trying to find a symbolic solution before falling back to the numerical integration.

A little math reading today

Freeman Dyson considers frog and bird mathematicians: those who work with the details, and those who take the broad view.

Crumpled paper and constructive mathematics

Victoria Gould combines acting and mathematics

Lotus Symphony lives

I'm a PC dinosaur, so I spent many pleasant hours learning and using Lotus Symphony before MS Office took over. It turns out that Symphony is still available, and free, to boot.

Short article here

IBM download page here

Worth reading today

Renaissance astronomer Tyco Brahe to be exhumed; foul play suspected.

Screen reading encourages sloth

Derbyshire reviews quantum physics book

Taking the earth's temperature ... 500 years ago

HP 35s Tear Down at embedded.com (updated)

Editor in Chief Richard Ness breaks open the calculator, and finds two ICs and twenty-five screws. Mr. Ness also discusses the design with Sam Kim, director of product development for HP calculators. Mr. Kim notes

Unlike one of the predecessor models (the 41), there's no way for the user to tap in to the 35s' firmware. The programming only occurs at the user level, although HP is tinkering with giving users limited access to the firmware.

Kim offers, "The 35s is pretty much hacker-proof, but the old 41 had a lot of hacking going on because it was more of an open platform. There was something called synthetic programming, and there was a crowd that evolved around it. I was actually a member of that crowd, the diehard HP users."

Update: Mr. Nass also made a short video discussing the teardown, available at the EE Times trade journal site.

HP 35s at HP

... first class animal protein ...

The Register found a Pravda article debunking the virtues of vegetarianism. Which is unintentionally funny, and so hard to take too seriously. For example:

Each and every human cell is supposed to be supplied with first class animal protein.

Furthermore, cosmetologists say that a typical vegetarian has dry and fragile hair, dull eyes and unhealthy complexion. They can hardly stand criticism and have a low boiling point. They raise their voice, swing their arms and splutter when arguing. They are weak even in their logic. They exemplify their righteousness with the cow, a herbivorous animal, and say that nature originally made a human being as a vegetarian creature.

The original Pravda link is a little racy. I had never been to the Pravda site, so I had assumed that Pravda was a reputable (so to speak) newspaper, but it looks a lot more like the National Enquirer.