jm + maths   11

'Mathwashing,' Facebook and the zeitgeist of data worship
Fred Benenson: Mathwashing can be thought of using math terms (algorithm, model, etc.) to paper over a more subjective reality. For example, a lot of people believed Facebook was using an unbiased algorithm to determine its trending topics, even if Facebook had previously admitted that humans were involved in the process.
maths  math  mathwashing  data  big-data  algorithms  machine-learning  bias  facebook  fred-benenson 
6 days ago by jm
_What We Know About Spreadsheet Errors_ [paper]
As we will see below, there has long been ample evidence that errors in spreadsheets are pandemic. Spreadsheets, even after careful development, contain errors in one percent or more of all formula cells. In large spreadsheets with thousands of formulas, there will be dozens of undetected errors. Even significant errors may go undetected because formal testing in spreadsheet development is rare and because even serious errors may not be apparent.
business  coding  maths  excel  spreadsheets  errors  formulas  error-rate 
october 2015 by jm
The Pixel Factory
amazing slideshow/WebGL demo talking about graphics programming, its maths, and GPUs
maths  graphics  webgl  demos  coding  algorithms  slides  tflops  gpus 
september 2015 by jm
A higher order estimate of the optimum checkpoint interval for restart dumps
the bottom line is as follows:
If the time it takes to create a dump, δ < M/2 then use τopt = √(2δM) – δ
Otherwise (it takes longer than M/2 to create a dump), just use τopt = M.
dumping  periodic-tasks  scheduling  frequency  maths  optimal  interval  checkpointing 
june 2015 by jm
the "Unknown Pleasures" cover, emulated in Mathematica
In July 1967, astronomers at the Cavendish Laboratory in Cambridge, observed an unidentified radio signal from interstellar space, which flashed periodically every 1.33730 seconds. This object flashed with such regularity that it was accurate enough to be used as a clock and only be off by one part in a hundred million.

It was eventually determined that this was the first discovery of a pulsar, CP-1919.  This is an object that has about the same mass as the Sun, but is the size of the San Francisco Bay at its widest (~20 kilometers) that is rotating so fast that its emitting a beam of light towards Earth like a strobing light house! Pulsars are neutron stars that are formed from the remnants of a massive star when it experiences stellar death.

A hand drawn graph plotted in the style of a waterfall plot, in the Cambridge Encyclopedia of Astronomy, later became renown for its use on the cover of the album "Unknown Pleasures"  by 1970s English band Joy Division.

The entire blog at is pretty great. Lots of nice mathematical animated GIFs, accompanied by Mathematica source and related ponderings.
maths  gifs  animation  art  unknown-pleasures  mathematica  cp-1919  pulsars  astronomy  joy-division  waterfall-plots  cambridge  blogs 
december 2014 by jm
'Addressing the rebalancing problem in bike-sharing systems' [paper]
Many of the bike-sharing systems introduced around the world in the past 15 years have the same problem: Riders tend to take some routes and not others. As a result, the bikes tend to collect in a few places, which is a drag for users and a costly problem for the operators, who "rebalance" the system using trucks that take bikes from full stations to empty ones. Now, scientists are coming up with special algorithms to improve this process. One of them, developed by scientists at the Vienna University of Technology and the Austrian Institute of Technology, is now being tested in Vienna's bike-sharing system; another, developed at Cornell University, is already in use in New York City.

Timely -- here's what Dublin Bikes looked like this morning:

(via Andrew Caines)
cycling  bike-sharing  borisbikes  dublinbikes  rebalancing  fleet  availability  optimization  maths  papers  toread  algorithms 
august 2014 by jm
Nassim Taleb: retire Standard Deviation
Use the mean absolute deviation [...] it corresponds to "real life" much better than the first—and to reality. In fact, whenever people make decisions after being supplied with the standard deviation number, they act as if it were the expected mean deviation.'

Graydon Hoare in turn recommends the median absolute deviation. I prefer percentiles, anyway ;)
statistics  standard-deviation  stddev  maths  nassim-taleb  deviation  volatility  rmse  distributions 
january 2014 by jm
East Texas Judge Says Mathematical Algorithms Can’t Be Patented, Dismisses Uniloc Claim Against Rackspace
This seems pretty significant. Is the tide turning in the Texas Eastern District against patent trolls, at last? And does it establish sufficient precedent?

A federal judge has thrown out a patent claim against Rackspace, ruling that mathematical algorithms can’t be patented. The ruling in the Eastern Disrict stemmed from a 2012 complaint filed by Uniloc USA asserting that processing of floating point numbers by the Linux operating system was a patent violation.

Chief Judge Leonard Davis based the ruling on U.S. Supreme Court case law that prohibits the patenting of mathematical algorithms. According to Rackspace, this is the first reported instance in which the Eastern District of Texas has granted an early motion to dismiss finding a patent invalid because it claimed unpatentable subject matter.

Red Hat, which supplies Linux to Rackspace, provided Rackspace’s defense. Red Hat has a policy of standing behind customers through its Open Source Assurance program.

See for more discussion.
east-texas  patents  swpats  maths  patenting  law  judges  rackspace  linux  red-hat  uniloc-usa  floating-point 
march 2013 by jm
The Mathematical Hacker
'The trouble with the Lisp-hacker tradition is that it is overly focused on the problem of programming -- compilers, abstraction, editors, and so forth -- rather than the problems outside the programmer's cubicle. I conjecture that the Lisp-school essayists -- Raymond, Graham, and Yegge -- have not “needed mathematics” because they spend their time worrying about how to make code more abstract. This kind of thinking may lead to compact, powerful code bases, but in the language of economics, there is an opportunity cost.'
mathematics  coding  maths  essay  hackers  lisp  fortran 
december 2012 by jm
Bayes' theorem ruled inadmissible in UK law courts
Bayes' theorem, and 'similar statistical analysis', ruled inadmissible in UK law courts (via Tony Finch)
uk  law  guardian  via:fanf  bayes  maths  statistics  legal 
october 2011 by jm
Kaprekar's constant
'6174 .. is notable for the following property: Take any four-digit number, using at least two different digits. (Leading zeros are allowed.); Arrange the digits in ascending and then in descending order to get two four-digit numbers, adding leading zeros if necessary; Subtract the smaller number from the bigger number; Go back to step 2. The process will reach 6174 in at most 7 iterations'
6174  constants  cool  maths  mathematics  numbers  kaprekar  wow  from delicious
august 2010 by jm

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