Eikonal Blog

2016.08.24

Approximate numerics

Filed under: Uncategorized — sandokan65 @ 21:22

~1700BCE Babylon: \sqrt{2} \approx 1 + \frac{24}{60} + \frac{51}{60^2} + \frac{10}{60^3} \approx 1.414,213

pi

Filed under: Uncategorized — sandokan65 @ 21:19

Seen somewhere recently:

  • \frac\pi4 = \frac11 - \frac13 + \frac15 - \frac17 + \cdots
  • \frac{\pi^2}6 = \frac1{1^1} + \frac1{2^2} + \frac1{3^2} + \cdots
  • \frac2\pi = \left(1-\frac13\right)\left(1+\frac15\right)\left(1-\frac17\right)\left(1-\frac1{11}\right)\left(1+\frac1{13}\right)\left(1+\frac1{17}\right)\cdots where fractional terms \frac1p are over all primes, and the sign in front of them is minus if p=4n-1 and plus otherwise.

2015.06.03

SourceForge has lost its common sense

Filed under: it, tools — Tags: , , , — sandokan65 @ 13:46

For long time the SourceForge was one of the most trusted open source projects repositories, where one could go to download the latest versions of numerous useful applications. They were a site safe from influence of various shady commercial interests, providing the installers and binaries as they are built by the project developers.

Few days ago it was announced on several technical sites that SourceForge has changed its business practice, and that it had went the CNET’s download.com way: they now repackage original installers into their own wrapper installers that (beside starting the contained original installer of the application one is interested in) perform drive-by installations of various cr*pware (adware, shareware, etc).

Following articles illustrate what is know about that change at this moment:

An afterthought: The same company that owns SourceForge is also owner of SlashDot discussion forum/site. So, I expect that they will go down the drain soon, too.

Update: Apparently this is going on for some time now:

Related: “C|Net’s Download.Com trojans” – https://eikonal.wordpress.com/2011/12/06/cnets-download-com-trojans/

2014.04.25

Denialism of science

Filed under: business, climate, cosmology, critical thinking, denialism, ecology, education, evolution, future, paleontology, propaganda, religion, science, society — Tags: , , , , , , , , — sandokan65 @ 09:13
  • Denialism (WikiPedia) – http://en.wikipedia.org/wiki/Denialism
    • In human behavior, denialism is exhibited by individuals choosing to deny reality as a way to avoid dealing with an uncomfortable truth. … “[It] is the refusal to accept an empirically verifiable reality. It is an essentially irrational action that withholds validation of a historical experience or event”. … group denialism [is defined] as “when an entire segment of society, often struggling with the trauma of change, turns away from reality in favor of a more comfortable lie.”
    • In science, denialism has been defined as the rejection of basic concepts that are undisputed and well-supported parts of the scientific consensus on a topic in favor of ideas that are both radical and controversial. … It has been proposed that the various forms of denialism have the common feature of the rejection of overwhelming evidence and the generation of a controversy through attempts to deny that a consensus exists. … A common example is Young Earth creationism and its dispute with the evolutionary theory.

2014

  • “How To Convince Conservative Christians That Global Warming Is Real” by Chris Mooney (Mother Jones; 2014.05.02) – http://www.motherjones.com/environment/2014/05/inquiring-minds-katharine-hayhoe-faith-climate
  • “Most Americans doubt Big Bang, not too sure about evolution, climate change – survey” By Rik Myslewski (The Register; 2014.04.21) – http://www.theregister.co.uk/2014/04/21/most_americans_doubt_big_bang_not_too_sure_about_evolution_climate_change_survey/
    • Science no match for religion, politics, business interests

    survey_results

  • “AP-GfK Poll: Big Bang a big question for most Americans” (AP-Gfk; 2014.04.21) – http://ap-gfkpoll.com/featured/findings-from-our-latest-poll-2
    • Few Americans question that smoking causes cancer. But they express bigger doubts as concepts that scientists consider to be truths get further from our own experiences and the present time … Americans have more skepticism than confidence in global warming, the age of the Earth and evolution and have the most trouble believing a Big Bang created the universe 13.8 billion years ago….
    • Just 4 percent doubt that smoking causes cancer, 6 percent question whether mental illness is a medical condition that affects the brain and 8 percent are skeptical there’s a genetic code inside our cells. More – 15 percent – have doubts about the safety and efficacy of childhood vaccines …
    • About 4 in 10 say they are not too confident or outright disbelieve that the earth is warming, mostly a result of man-made heat-trapping gases, that the Earth is 4.5 billion years old or that life on Earth evolved through a process of natural selection, though most were at least somewhat confident in each of those concepts. But a narrow majority – 51 percent – questions the Big Bang theory …
    • “Science ignorance is pervasive in our society, and these attitudes are reinforced when some of our leaders are openly antagonistic to established facts,”…
    • The poll highlights “the iron triangle of science, religion and politics,” … And scientists know they’ve got the shakiest leg in the triangle….
    • To the public “most often values and beliefs trump science” when they conflict, … … Political values were closely tied to views on science in the poll, with Democrats more apt than Republicans to express confidence in evolution, the Big Bang, the age of the Earth and climate change….
    • Religious values are similarly important… Confidence in evolution, the Big Bang, the age of the Earth and climate change decline sharply as faith in a supreme being rises, according to the poll. Likewise, those who regularly attend religious services or are evangelical Christians express much greater doubts about scientific concepts they may see as contradictory to their faith … “When you are putting up facts against faith, facts can’t argue against faith,” … “It makes sense now that science would have made no headway because faith is untestable.” …
    • Beyond religious belief, views on science may be tied to what we see with our own eyes. The closer an issue is to our bodies and the less complicated, the easier it is for people to believe, …
    • Marsha Brooks, a 59-year-old nanny who lives in Washington, D.C., said she’s certain smoking causes cancer because she saw her mother, aunts and uncles, all smokers, die of cancer … But when it comes to the universe beginning with a Big Bang or the Earth being about 4.5 billion years old, she has doubts. …
    • Jorge Delarosa, a 39-year-old architect from Bridgewater, N.J., pointed to a warm 2012 without a winter and said, “I feel the change. There must be a reason.” But when it came to Earth’s beginnings 4.5 billion years ago, he has doubts simply because “I wasn’t there.”…
    • Experience and faith aren’t the only things affecting people’s views on science. … “the force of concerted campaigns to discredit scientific fact” as a more striking factor, citing significant interest groups – political, business and religious – campaigning against scientific truths on vaccines, climate change and evolution….
    • … sometimes science wins out even against well-financed and loud opposition, as with smoking. Widespread belief that smoking causes cancer “has come about because of very public, very focused public health campaigns,” … [also, what is very encouraging is] the public’s acceptance that mental illness is a brain disease, something few believed 25 years ago, before just such a campaign.
  • “Why climate deniers are winning: The twisted psychology that overwhelms scientific consensus” by Paul Rosenberg (The Salon; 2014.04.19) – http://www.salon.com/2014/04/19/why_climate_deniers_are_winning_the_twisted_psychology_that_overwhelms_scientific_consensus/
    • There’s a reason why overwhelming evidence hasn’t spurred public action against global warming
    • “The reason ‘consensus’ has not appeared to work in society at large to date isn’t because it’s ineffective – it’s because there is a well-funded counter-movement out there that takes every opportunity to mislead the public into thinking that there isn’t a consensus,”
  • “How politics makes us stupid” by Ezra Klein (Vox; 2014.04.06) – http://www.vox.com/2014/4/6/5556462/brain-dead-how-politics-makes-us-stupid

Older articles

  • “How Do You Get People to Give a Damn About Climate Change?” by Chris Mooney (Mother Jones; 2013.10.18) – http://www.motherjones.com/environment/2013/10/inquiring-minds-kahan-lewandowsky-communicate-climate
    • Experts have come a long way in figuring out which messages can successfully open minds and move public opinion. There’s just one problem: They disagree about whether the message everyone’s using actually works.
  • “Scientific uncertainty and climate change: Part I. Uncertainty and unabated emissions” by Stephan Lewandowsky, James S. Risbey, Michael Smithson, Ben R. Newell, John Hunter (Springer) – http://link.springer.com/article/10.1007/s10584-014-1082-7
    • Uncertainty forms an integral part of climate science, and it is often used to argue against mitigative action. This article presents an analysis of uncertainty in climate sensitivity that is robust to a range of assumptions. We show that increasing uncertainty is necessarily associated with greater expected damages from warming, provided the function relating warming to damages is convex. This constraint is unaffected by subjective or cultural risk-perception factors, it is unlikely to be overcome by the discount rate, and it is independent of the presumed magnitude of climate sensitivity. The analysis also extends to “second-order” uncertainty; that is, situations in which experts disagree. Greater disagreement among experts increases the likelihood that the risk of exceeding a global temperature threshold is greater. Likewise, increasing uncertainty requires increasingly greater protective measures against sea level rise. This constraint derives directly from the statistical properties of extreme values. We conclude that any appeal to uncertainty compels a stronger, rather than weaker, concern about unabated warming than in the absence of uncertainty.
  • “Scientific uncertainty and climate change: Part II. Uncertainty and mitigation” by Stephan Lewandowsky, James S. Risbey, Michael Smithson, Ben R. Newell (Springer) – http://link.springer.com/article/10.1007/s10584-014-1083-6
    • In public debate surrounding climate change, scientific uncertainty is often cited in connection with arguments against mitigative action. This article examines the role of uncertainty about future climate change in determining the likely success or failure of mitigative action. We show by Monte Carlo simulation that greater uncertainty translates into a greater likelihood that mitigation efforts will fail to limit global warming to a target (e.g., 2 °C). The effect of uncertainty can be reduced by limiting greenhouse gas emissions. Taken together with the fact that greater uncertainty also increases the potential damages arising from unabated emissions (Lewandowsky et al. 2014), any appeal to uncertainty implies a stronger, rather than weaker, need to cut greenhouse gas emissions than in the absence of uncertainty.
  • “The pivotal role of perceived scientific consensus in acceptance of science” by Stephan Lewandowsky, Gilles E. Gignac, Samuel Vaughan (Nature Climate Change 3, 399-404 (2013); doi:10.1038/nclimate1720; 2012.10.28) – http://www.nature.com/nclimate/journal/v3/n4/full/nclimate1720.html
    • Although most experts agree that CO2 emissions are causing anthropogenic global warming (AGW), public concern has been declining. One reason for this decline is the ‘manufacture of doubt’ by political and vested interests, which often challenge the existence of the scientific consensus. The role of perceived consensus in shaping public opinion is therefore of considerable interest: in particular, it is unknown whether consensus determines people’s beliefs causally. It is also unclear whether perception of consensus can override people’s ‘worldviews’, which are known to foster rejection of AGW. Study 1 shows that acceptance of several scientific propositions-from HIV/AIDS to AGW-is captured by a common factor that is correlated with another factor that captures perceived scientific consensus. Study 2 reveals a causal role of perceived consensus by showing that acceptance of AGW increases when consensus is highlighted. Consensus information also neutralizes the effect of worldview.

Related:

2014.04.21

We don’t need stinking renewable energy ….

Filed under: anticompetitive behavior, business, denialism, society — Tags: , , , — sandokan65 @ 09:20

There is new trend seen in couple of mid-western states to make new laws that discourage individual house owners to use renewable energy (solar and wind).

  • “Op-Ed: ALEC and the Koch brothers fight solar energy with surcharges” by Justin King (2014.04.21) – http://www.digitaljournal.com/news/politics/op-ed-alec-and-the-koch-brothers-fight-solar-energy-with-surcharges/article/381659
  • “Oklahoma Will Charge Customers Who Install Their Own Solar Panels” by Kiley Kroh (Climate Progress; 2014.04.16) – http://thinkprogress.org/climate/2014/04/16/3427392/oklahoma-fee-solar-wind/
    • New law (S.B. 1456), passed the state House 83-5 after no debate. Those who install distributed power generation systems like solar panels or small wind turbines on their property and sell the excess energy back to the grid will be charged a monthly fee. Bill was pushed through quietly, out of nowhere, attached to some other bill. The main beneficiary of the bill, Oklahoma Gas and Electric Co., play here double track: for their own use of wind power they are getting tax credits, while suppressing the customers who use wind power on their own.
    • This is a trend in multiple states, where there is push by the power companies to punish the local customers who are participating in “net metering” (i.e. being compensated for the excess electric power they sell to the utility company). “Net metering laws have come under fire from the secretive American Legislative Exchange Council (ALEC), a group backed by fossil fuel corporations, utility companies, and the ultra-conservative Koch brothers. Forty-three states and the District of Columbia currently have net metering policies in place and ALEC has set its sights on repealing them, referring to homeowners with their own solar panels as “freeriders on the system.” … Net metering survived attacks in Colorado and Kansas and Vermont recently increased its policy in a bipartisan effort. Last year, Arizona added what amounts to a $5 per month surcharge for solar customers, a move that was widely seen as a compromise, particularly after ALEC and other Koch-backed groups got involved.”

Related:

2014.03.19

Antivaccination movement

Filed under: critical thinking, health, society — Tags: , , , , , , , , — sandokan65 @ 10:54

News

Concequences

Autism vs MMR vaccination – a nonexisting link

Related:

2014.01.21

Killing intelligent life (Taiji Cove Massacre)

Filed under: opression — Tags: , , , , , , , , , , , , , , , , — sandokan65 @ 13:28

The annual dolphin slaughter in Taiji, Japan

Faroe Islands’ Pilot Whales Slaughter

More at this blog: Intelligence in Earth’s nonhuman life – https://eikonal.wordpress.com/2011/05/23/intelligence-in-earths-other-life/

2013.11.26

Checks and balances

Filed under: business, economy, society — Tags: , , , , , , , , — sandokan65 @ 10:59

Some mechanism to keep society relatively livable for majority of population.

Capping executive pay

Term limits

2013.11.24

Poverty

Filed under: education, health, mind & brain, society — Tags: , , , — sandokan65 @ 09:26

2013.11.21

Peopling of Americas

Filed under: anthropology, evolution, geneaology, history, past — Tags: , , — sandokan65 @ 10:43

2014

  • “Discoveries Challenge Beliefs on Humans’ Arrival in the Americas” by Simon Rommero (The New York Times; 2014.03.27) – http://www.nytimes.com/2014/03/28/world/americas/discoveries-challenge-beliefs-on-humans-arrival-in-the-americas.html?_r=0
    • Researchers here say they have unearthed stone tools proving that humans reached what is now northeast Brazil as early as 22,000 years ago. Their discovery adds to the growing body of research upending a prevailing belief of 20th-century archaeology in the United States known as the Clovis model, which holds that people first arrived in the Americas from Asia about 13,000 years ago.
    • More recently, numerous findings have challenged that narrative. In Texas, archaeologists said in 2011 that they had found projectile points showing that hunter-gatherers had reached another site, known as Buttermilk Creek, as early as 15,500 years ago. Similarly, analysis of human DNA found at an Oregon cave determined that humans were there 14,000 years ago.

      But it is in South America, thousands of miles from the New Mexico site where the Clovis spear points were discovered, where archaeologists are putting forward some of the most profound challenges to the Clovis-first theory.

      Paleontologists in Uruguay published findings in November suggesting that humans hunted giant sloths there about 30,000 years ago. All the way in southern Chile, Tom D. Dillehay, an anthropologist at Vanderbilt University, has shown that humans lived at a coastal site called Monte Verde as early as 14,800 years ago.

    • In what may be another blow to the Clovis model of humans’ coming from northeast Asia, molecular geneticists showed last year that the Botocudo indigenous people living in southeastern Brazil in the late 1800s shared gene sequences commonly found among Pacific Islanders from Polynesia.
  • “Native Americans Descend From Ancient Montana Boy” (Science; 2014.02.12) – http://news.sciencemag.org/archaeology/2014/02/native-americans-descend-ancient-montana-boy

2013

  • “DNA reveals details of the peopling of the Americas” by Tina Hesman Saey (Science news; 2013.11.21) – https://www.sciencenews.org/article/dna-reveals-details-peopling-americas
    • Migrants came in three distinct waves that interbred once in the New World
    • About 15,000 to 18,000 years ago, the first migrant wave spilled from Asia down the Pacific coast and then pushed inland, eventually peopling the land from “the tip of South America all the way to Hudson Bay,” says Andrew Kitchen, a genetic anthropologist at the University of Iowa who was not involved in the new research. That first migrant wave contained the ancestors of all South and Central American tribes, and North Americans, too. But something different was going on in North America, an international team of researchers has discovered.
    • A second wave of migration probably left Siberia only a couple thousand years after the first wave. Instead of trickling down the coast, the second group slipped through an ice-free corridor running from Alaska into what is now southern Canada, the team found. The second wave never made it south of the present-day United States. The mixture of first-wave and second-wave genetic signatures in some Native Americans today indicates that the newcomers and existing populations interbred.
    • A third wave of migration started around 4,000 years ago in Alaska and swept mostly eastward across Canada.
    • Previous studies of human migration into the Americas have sometimes focused on two types of languages that emerged among the tribes: the Na-Dene language family, including Navajo, Apache and Tlingit, and non-Na-Dene languages, including Algonquin, Ojibwe and Chippewa. Scientists had thought the language groups reflected genetic separation, with the second wave being restricted to the Na-Dene language family. But Torroni and his colleagues discovered that second-wave genetic marks occurred in people who spoke languages from both groups. The finding suggests that the languages developed after the people arrived, and gives a more dynamic picture of what was happening in eastern North America, says Kitchen.
  • “DNA testing on 24,000-year-old skeleton reveals that Native Americans could have EUROPEAN origins” by Ellie Zolfagharifard (MailOnline; 2013.11.21) – http://www.dailymail.co.uk/sciencetech/article-2511172/DNA-testing-24-000-year-old-skeleton-reveals-Native-Americans-EUROPEAN-origins.html
    • The genome of the four-year-old boy is the oldest sequenced to date
    • DNA from the remains, discovered in Siberia in the 1920s, are thought to contain a third of Native American ancestry’s gene pool
    • Interestingly, the boy showed no similarities with populations in East Asia
  • “Ancient Bone of 24,000-Year-Old Siberian Youth Shows Native Americans had West Eurasian Origins” by Kathleen Lee (Science World Report; 2013.11.21) – http://www.scienceworldreport.com/articles/11072/20131121/ancient-bone-of-24-000-year-old-siberian-youth-shows-native-americans-had-west-eurasian-origins.htm
  • “DNA indicates Eurasian roots for Native Americans, new study says” by Meeri Kim (The Washington Post; 2013.11.20) – http://www.washingtonpost.com/national/health-science/fossil-indicates-eurasian-roots-for-native-americans/2013/11/20/2777ac24-51fa-11e3-a7f0-b790929232e1_story.html
  • “24,000-Year-Old Body Shows Kinship to Europeans and American Indians” by NICHOLAS WADE (The New York Times; 2013.11.20) – http://www.nytimes.com/2013/11/21/science/two-surprises-in-dna-of-boy-found-buried-in-siberia.html
  • “”Great Surprise”—Native Americans Have West Eurasian Origins” by Brian Handwerk (National Geographic; 2013.11.20) – http://news.nationalgeographic.com/news/2013/11/131120-science-native-american-people-migration-siberia-genetics
    • Oldest human genome reveals less of an East Asian ancestry than thought.
    • Nearly one-third of Native American genes come from west Eurasian people linked to the Middle East and Europe, rather than entirely from East Asians as previously thought, according to a newly sequenced genome.
  • “Upper Palaeolithic Siberian genome reveals dual ancestry of Native Americans” (Nature; 2013.11.20) – http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12736.html
    • Abstract: The origins of the First Americans remain contentious. Although Native Americans seem to be genetically most closely related to east Asians1, 2, 3, there is no consensus with regard to which specific Old World populations they are closest to4, 5, 6, 7, 8. Here we sequence the draft genome of an approximately 24,000-year-old individual (MA-1), from Mal’ta in south-central Siberia9, to an average depth of 1×. To our knowledge this is the oldest anatomically modern human genome reported to date. The MA-1 mitochondrial genome belongs to haplogroup U, which has also been found at high frequency among Upper Palaeolithic and Mesolithic European hunter-gatherers10, 11, 12, and the Y chromosome of MA-1 is basal to modern-day western Eurasians and near the root of most Native American lineages5. Similarly, we find autosomal evidence that MA-1 is basal to modern-day western Eurasians and genetically closely related to modern-day Native Americans, with no close affinity to east Asians. This suggests that populations related to contemporary western Eurasians had a more north-easterly distribution 24,000 years ago than commonly thought. Furthermore, we estimate that 14 to 38% of Native American ancestry may originate through gene flow from this ancient population. This is likely to have occurred after the divergence of Native American ancestors from east Asian ancestors, but before the diversification of Native American populations in the New World. Gene flow from the MA-1 lineage into Native American ancestors could explain why several crania from the First Americans have been reported as bearing morphological characteristics that do not resemble those of east Asians2, 13. Sequencing of another south-central Siberian, Afontova Gora-2 dating to approximately 17,000 years ago14, revealed similar autosomal genetic signatures as MA-1, suggesting that the region was continuously occupied by humans throughout the Last Glacial Maximum. Our findings reveal that western Eurasian genetic signatures in modern-day Native Americans derive not only from post-Columbian admixture, as commonly thought, but also from a mixed ancestry of the First Americans.
  • “Disputed finds put humans in South America 22,000 years ago” by Bruce Bower (*Science News; 2013.04.20) – https://www.sciencenews.org/article/disputed-finds-put-humans-south-america-22000-years-ago
    • Brazilian site may have been home to people before the Clovis hunters
    • C. Lahaye et al. Human occupation in South America by 20,000 BC: The Toca da Tira Peia site, Piaui, Brazil. Journal of Archaeological Science. Doi: 10.1016/j.jas.2013.02.019.

2012

2011

  • “Stone tools cut swathe through Clovis history” by Matt Kaplan (nature; 2011.03.24) – http://www.nature.com/news/2011/110324/full/news.2011.185.html
    • Dig uncovers previously unknown North American culture.
    • The long-standing idea that the Clovis people of ancient North America were the first tool-using humans on the continent 13,200 years ago is being overturned by the discovery of human artefacts in a Texan creek bed that are even older.

2013.08.13

Near-Death Experiences

Filed under: mind & brain — Tags: , — sandokan65 @ 09:17

2013.08.06

Applied graph theory (“Social Networks Analysis”)

Filed under: complexity, mathematics, networking, science, small worlds — Tags: , , , , , , , — sandokan65 @ 15:11

Concepts

Graph theory:

  • nodes and edges
  • degree = number of edges for a given node
  • isolated nodes
  • connected nodes
  • hub = well connected node
  • Scale-free networks = average number of nodes stays constant
  • preferential attachment:
    • the fraction of nodes with k edges: p(k) \sim k^{-\gamma}
    • a long tail distribution
  • Degree of distribution

SNAs on YouTube

Six degrees of separation, Small Worlds, Kevin Bacon metric, Erdos metric, etc

Books

Authors and Sites

Papers

  • “Power laws, Pareto distributions and Zipf’s law” by M.E.J. Newman (arXiv) – http://arxiv.org/abs/cond-mat/0412004
    • When the probability of measuring a particular value of some quantity varies inversely as a power of that value, the quantity is said to follow a power law, also known variously as Zipf’s law or the Pareto distribution. Power laws appear widely in physics, biology, earth and planetary sciences, economics and finance, computer science, demography and the social sciences. For instance, the distributions of the sizes of cities, earthquakes, solar flares, moon craters, wars and people’s personal fortunes all appear to follow power laws. The origin of power-law behaviour has been a topic of debate in the scientific community for more than a century. Here we review some of the empirical evidence for the existence of power-law forms and the theories proposed to explain them.
    • more papers by M.E.J. Newman at arXiv – arxiv.org/find/cond-mat/1/au:+Newman_M/0/1/0/all/0/1

2013.07.02

Intentional loss of functionality (arrogance of Atlassian, Mozilla, Microsoft)

Filed under: business, it, knowledgeManagement — Tags: , , — sandokan65 @ 11:02

It appears that every modern tech company feels that it is a home of bunch of visionaries, of technical prodigies that are entitled to keep changing user experience (of their products) all the time. Adding new features would be fine. Providing alternate (frequently better) ways of doing something (that was already doable within product) is also fine. Removing long present features is not fine. Doing so is akin to an invitation to an religions war. It insults users by implying that developer knows better that all users what is better for them. Is every developer under impression that he has to do bold arrogant moves like Steve Jobs use to do or Microsoft does all the time?

Few recent examples follow.

1) Atlassian Confluence wiki removal of wiki markup

Confluence used to be one of the best wiki engines. Rich in features, suitable for corporate deployment. Its downsides are that it is written in Java, hard to install and properly configure – but if you have someone else take these administrative jobs from your hand, it used to be very powerful knowledge management platform.

In version 4 of Confluence, the Atlassian removed the wiki markup editor.

2) Firefox removing users’ ability to switch off JavaScript

Come again? What is the next, removing the navigation/URL window so users can go only to predefined links on their home portals?

Comment added later:

3) FireFox removed right-click option to send a page link

FireFox Right Click

 

Since version 16 of Mozilla’s FireFox browser, that options is removed. Now it can be found under the File > Send Link location.

FireFox Right Click 2

This is a minor annoyance. One can either reprogram his mind and start using the new location, or install extension “Send Link in context menu” (https://addons.mozilla.org/en-US/firefox/addon/send-link-in-context-menu/).

2013.02.26

Facebook sinking even deeper

Filed under: FaceBook, opression, privacy, propaganda, surveillance, tracking — Tags: , , , , , — sandokan65 @ 09:27

2013.01.14

Android development

Filed under: java, mobile and wireless, programming languages — Tags: , — sandokan65 @ 13:19

2013.01.03

Brain games

Filed under: Uncategorized — Tags: , , , , , — sandokan65 @ 14:02

Sites

Dual N-back

Other

Elsewhere in this blog: Intelligence (IQ) – https://eikonal.wordpress.com/2010/10/27/intelligence/

2012.11.26

Generating functions

Filed under: fun, mathematics, number theory — Tags: , , , , , , , , , , , , , , , , , , , — sandokan65 @ 13:53

Recently I have been rereading the Herbert S. Wilf’s free online book Generatingfunctionology – http://www.math.upenn.edu/~wilf/DownldGF.html. It is choke-full of interesting results.

Definitions

For a number series {\bf a} :\equiv \{a_n|n\in\{0,\infty\}\} one defines following generating functions (GFs):

  • Ordinary Power Series GF (OPSGF): OPSGF[a](x) :\equiv \sum_{n=0}^\infty a_n x^n \leftrightarrow_{opsgf} {\bf a};
  • Exponential Series GF (EGF): EGF[a](x) :\equiv \sum_{n=0}^\infty a_n \frac{x^n}{n!} \leftrightarrow_{egf} {\bf a};
  • Dirichlet GF (DGF): DGF(x;s) :\equiv \sum_n \frac{a_n}{n^s} x^n \leftrightarrow_{dgf} {\bf a};
  • Lambert GF (LGF): LGF(x) :\equiv \sum_n \frac{a_n}{1-x^n} x^n \leftrightarrow_{lgf} {\bf a};
  • Bell GF (BGF): BGF(x;s) :\equiv \sum_n a_{p^n} x^n \leftrightarrow_{bgf} {\bf a};
  • Poisson GF (PGF): PGF(x;s) :\equiv \sum_n \frac{a_n}{n!} x^n e^{-x} = e^{-x} EGF(x) \leftrightarrow_{pgf} {\bf a};

Simple results

  • \{a_n=n\} \leftrightarrow_{opsgf} f(x) = \frac{x}{(1-x)^2}.
  • \{a_n=n^2\} \leftrightarrow_{opsgf} f(x) = \frac{x(x+1)}{(1-x)^3}.
  • \{a_n=b^n\} \leftrightarrow_{opsgf} f(x) = \frac{1}{1-b x}.
  • \{a_n=n\} \leftrightarrow_{egf} f(x) = x e^{x}.
  • \{a_n=n^2\} \leftrightarrow_{egf} f(x) = x(x+1)e^{x}.
  • \{a_n=b^n\} \leftrightarrow_{egf} f(x) = e^{b x}.
  • For Fibonacci numbers \{F_n|F_{n+1} = F_n + F_{n-1} | f_0 = F_1 = 1\} one has: OPSGF(x) = \frac{x}{1-x-x^2}, leading to F_n = \frac{r_+^n-(r_-^n}{\sqrt{5}} (r_\pm = \frac{1\pm\sqrt{5}}{2}).
  • \{a_n|a_{n+1}=2 a_n + 1| a_0=0\} \leftrightarrow_{opsgf} OPSGF = \frac{x}{(1-x)(1-2x)} = \frac{1}{1-2x} - \frac{1}{1-x}; which leads to a_n=2^n - 1.
  • For a_{n+1} = 2 a_n + n, $alatex _0=1$ one has: OPSGF = \frac{2}{1-2x} - \frac1{(1-x)^2} leading to
    a_n = 2^{n-1} - n - 1.

Define [x^n]f(x) as the coefficient next to x^n in power series f(x). Examples and properties:

  • [x^n] e^x = \frac1{n!},
  • [x^n] \frac1{1-ax} = a^n,
  • [x^n] (1+x)^s = \binom{s}{n},
  • [x^n] \{x^m f(x)\} = [x^{n-m}] f(x),
  • [\lambda x^n] f(x) = \frac1{\lambda} [x^n]f(x),
  • \left[\frac{x^n}{n!}\right] e^x = 1.

For binomial coeficients:

  • \sum_{k=0}^{\infty} \binom{n}{k} x^k = (1+x)^n,
  • \sum_{n=0}^{\infty} \binom{n}{k} y^n = \frac{y^k}{(1-y)^{k+1}},
  • \binom{n}{k} = [x^k y^n] \frac1{1 - y (1+x)}.

Some orthogonal polynomials:

  • Tchebitshev polynomials generating function: \sum_{n=0}^\infty \frac{z^n}{n!} T_n(x) = e^{zx}\cos(z\sqrt{1-x^2}).
  • Legendre polynomials generating function: \frac1{(1-2tz+z^2)^{\frac12}} = \sum_{n=0}^\infty P_n(t)z^n.
  • Generating function for associated Legendre polynomials: (1-2tc+t^2)^{\alpha} = |1-t e^{i\theta}|^{2\alpha} = \sum_{n=0}^\infty t^n P_n^{\alpha}(c).

Dirichlet series generating functions

  • For a_n=1: DGF = \zeta(s).
  • For a_n=\mu(n) (the Moebius function): DGF = \frac1{\zeta(s)}.
  • For a_n=d(n)=\sigma_0(n) (the zeroth-order divisor function): DGF = \zeta(s)^2.
  • For a_n=\sigma_k(n) (the kth-order divisor function): DGF = \zeta(s)\zeta(s-k).
  • For a_n=\phi(n) (the totient function): DGF = \frac{\zeta(s-1)}{\zeta(s)}.
  • For a_n=H(n) (the number of ordered factorizations): DGF = \frac{1}{2 - \zeta(s)}.
  • For a_n=\frac12 [1-(-1)^n]: DGF = \lambda(s) (the Dirichlet lambda function).

Moebius inversion formula:

  • If two DGF series A(s) and B(s) have coefficient relation a_n = \sum_{d|n} b_d, then A(s) = B(s) \zeta(s), and b_n = \sum_{d|n} \mu\left(\frac{n}{d}\right) a_d.
  • If a_n = \sum_{d|n} b_d, then b_n = \sum_{d|n} \mu\left(\frac{n}{d}\right) a_d.

SciFi

Filed under: books, fun, scifi — Tags: , , — sandokan65 @ 13:49

Herbert George Wells

  • The Invisible Man
  • The New Machiavelli
  • The Time Machine
  • The War of the Worlds
  • The World Set Free
  • Time Machine

2012.11.02

Java keytool

Filed under: crypto, hashes, infosec, it, java — Tags: , — sandokan65 @ 10:45
  • Download the CA certificate from the proxy and convert it to PEM format: 

      /usr/java/default/bin/keytool -import -trustcacerts -file  -alias CA_ALIAS -keystore /usr/java/default/lib/security/cacerts -storepass changeit

More:

2012.06.27

This is getting tiresome: Facebook never stop monkeying with its users

Filed under: business, FaceBook, it, opression, propaganda, tracking — Tags: , , , , , , , — sandokan65 @ 08:25
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