C++11 feels like a new language. I write code differently now than I did in C++98. The C++11 code is shorter, simpler, and usually more efficient than what I used to write.

This poses challenges: How do you present C++? What techniques do you recommend? What language features and libraries do you emphasize? Presenting C++11 as a layer on top of C++98 would be as bad as representing C++98 as a layer on top of C. C++ must be presented as a whole, as the powerful tool for design and implementation that it is, rather than a set of independent features.

The Fourth Edition of The C++ Programming Language attempts that and should become available in a few months. To help people get started with C++11 and with TC++PL4, I summarize C++11 in four chapters, collectively named A Tour of C++. Addison-Wesley graciously allowed me to post drafts of these chapters. I will do so over the next months.

The physical register files hold the actual input and output operands for uops. The integer PRF added a modest 8 registers, bringing the total to 168. Given that AVX2 was a major change to Haswell, it should be no surprise that the number of 256-bit AVX registers grew substantially to accommodate the new integer SIMD instructions. Haswell features 24 extra physical registers for renaming YMM and XMM architectural registers. The branch order buffer, which is used to rollback to known good architectural state in the case of a misprediction is still 48 entries, as with Sandy Bridge. The load and store buffers, which are necessary for any memory accesses have grown by 8 and 6 entries respectively, bringing the total to 72 loads and 42 stores in-flight.

Unlike AMD’s Bulldozer, Haswell continues to use a unified scheduler that holds all different types of uops. The scheduler in Haswell is now 60 entries, up from 54 in Sandy Bridge, those entries are dynamically shared between the active threads. The scheduler holds uops that are waiting to execute due to resource or operand contraints. Once ready, uops are issued to the execution units through dispatch ports. While fused uops occupy a single entry in the ROB, execution ports can handle a single un-fused uop. So a fused load+ALU uop will occupy two ports to execute.

Haswell and Sandy Bridge both retire upto 4 fused uops/cycle, once all the constituent uops have been successfully executed. Retirement occurs in-order and clears out resources such as the ROB, physical register files and branch order buffer.

Kenneth Rogoff, Project Syndicate, Europe’s Lost Keynesians, here.

The eurozone’s difficulties, I have long argued, stem from European financial and monetary integration having gotten too far ahead of actual political, fiscal, and banking union. This is not a problem with which Keynes was familiar, much less one that he sought to address.

Read more at http://www.project-syndicate.org/commentary/a-structural-focus-for-the-euro-crisis-by-kenneth-rogoff#SCX8d9oaHgoMeZQS.99

The advent of cheap computing power has improved the reliability of some, but not all, types of predictions. Twenty-five years ago, the National Hurricane Center’s forecasts of a hurricane’s landfall three days out had a radius of uncertainty of 350 miles. Today, that error is down to 100 miles, an area small enough to effectively evacuate and harden. Weather forecasts rely on simulations of the atmosphere, built from equations representing well-understood physical laws and measurements of current conditions. These equations have proven highly reliable over decades, and advances in satellite and radar technology provide meteorologists with increasingly accurate and fine-grained data. Since doubling the resolution of these models requires a sixteen-fold increase in the number of calculations, computational capacity substantially limits predictive accuracy. Supercomputers help here.

But computer power can’t make up for faulty theory or poor quality data. A fundamental challenge facing modelers is that in most cases they can see only the effects of a random phenomenon, not the underlying processes that generate it. In cases of wild randomness, relying on computers to squeeze inferences from limited data sets leads experts to confidently discount the possibility of future black swans, which in turn encourages decision makers to over-optimize and reduce margins of safety too far. Silver demonstrates how competition among data-driven experts to produce “precise” forecasts for their consumers leads experts to try to reduce the uncertainty reported alongside their predictions. In doing so, analysts tend to “overfit” their models to more closely follow the contours of the available data. While this strategy might reduce the margins of error in their reports, it also yields models that judge events more extreme than those present in their source data to be virtually impossible. For businesses and regulators eager to keep compliance costs low, these truncated forecasts are often welcome news.

§1. Hodge-Arakelov-theoretic Motivation §2. Teichmu ̈ller-theoretic Deformations §3. The Log-theta-lattice §4. Inter-universality and Anabelian Geometry

OVER the last few weeks, as the stock market has reached new highs, my thoughts have turned to my 85-year-old mother.

“O.K. Mr. Smarty-Pants,” she often asks me, “what stock should I buy now?”

She first asked me this question when I was an undergraduate at Princeton, majoring in economics. She asked again when I was a graduate student at M.I.T., earning a Ph.D. in economics. And she has asked it regularly during the last three decades when I have been an economics professor at Harvard.

Brad DeLong, Grasping Reality, Equity Return and the Size of the Economy: Bill Gross Makes A Distressingly Common Error, here.

Bill Gross implicitly makes three assumptions: (i) that the total stock and bond valuations in the economy add up to the economy’s private corporate capital stock, (ii) that the capital stock of the economy cannot grow much faster than real GDP (currently projected to grow at between 2.5%/year and 3.0%/year), and (iii) that all transfers from corporations to savers–dividends and share backs and bond interest and principal payments–are reinvested in the market. If those three assumptions are true, then indeed the weighted average of stock and bond returns must be in the 2.5-3.0%/year range.

But assumption (iii) is wrong. When a company pays me money by buying back a share, I do not have to reinvest that money in the market. When a company pays me money by issuing a dividend, it does not have to raise that money from the market by selling a new stock or bond–it can (and does) raise that money from its customers by selling them goods and services at more than their cost of production. And if (iii) fails, then there is no necessary direct arithmetic connection between the rate of return on stocks and bonds and the growth rate of the economy.

Gold’s slump has saddled the second-largest U.S. college endowment with more than $300 million in paper losses. But the swoon hasn’t shaken the faith of Bruce Zimmerman, who since 2007 has been chief executive of University of Texas Investment Management Co.

“We always prefer that our assets go up, rather than down, but we’re not day traders,” said Mr. Zimmerman, whose company invests $29.5 billion for the benefit of the University of Texas and Texas A&M systems. “Gold is a hedge, and it still fills that role.”

Read more: http://www.businessinsider.com/kyle-bass-macro-tourist-2013-5#ixzz2U8gt8cQN

The dumb money is returning to Japan, in a big way. Mutual and exchange traded funds investing in Japanese shares attracted record inflows last week. So far this year almost as much money has gone into Japanese mutual funds as in the best two full years of the last decade.

It is unfair to label private investors “dumb”, but it is at least better than calling them muppets. Still, in the case of Japan, it is certainly true that they are late to the party.

Brad Stone, Bloomberg Businessweek, Inside Google’s Secret Lab, here.

As the polymath engineers and scientists who work there are fond of saying, Google X is the search giant’s factory for moonshots, those million-to-one scientific bets that require generous amounts of capital, massive leaps of faith, and a willingness to break things. Google X (the official spelling is Google [x]) is home to the self-driving car initiative and the Internet-connected eyeglasses, Google Glass, among other improbable projects.

 

Tyler Cowen has no truck with the Bubble Crew. He aligns himself with Paul Krugman and againstJesse Eisinger; we can add Gillian Tett to Eisinger’s side of the debate, and Jim Surowiecki to Cowen’s.

The bubblista side of the argument, at heart, says that the flood of money being poured into the global economy by the world’s central banks is driving up asset prices to well beyond fundamental valuations, and that if and when valuations revert to sanity, the unwind (the “burst”) could be disastrous in all manner of unpredictable ways.

Researchers of the Fraunhofer Institute for Applied Solid State Physics and the Karlsruhe Institute for Technology have achieved the wireless transmission of 40 Gbit/s at 240 GHz over a distance of one kilometer. Their most recent demonstration sets a new world record and ties in seamlessly with the capacity of optical fiber transmission. In the future, such radio links will be able to close gaps in providing broadband internet by supplementing the network in rural areas and places which are difficult to access.
Read more at: http://phys.org/news/2013-05-gbits-ghz-world-wireless-transmission.html#jCp

Yesterday, HPC in the Cloud discussed the prospect of running scientific computing applications in the cloud on Amazon’s CPU and GPU cores in EC2, particularly with regard to computational fluid dynamics. It is fitting then that HPC Experiment, a research initiative comprised of teams of IT engineers, experts, and analysts, hosted a presentation on the subject this week.

GLL, Twin Primes are Useful, here,

Yitang Zhang, of the University of New Hampshire, has apparently proved a finite approximation to the famous Twin Prime Conjecture. This is a result of the first order. After ten days of progressively more detailed news, including today’sarticle in the New York Times, Zhang’s 56-page preprinthas just been released on the Annals of Mathematics journal website. This may be a revision of the original submission, which was said in a story in Nature last week to have needed “a few minor tweaks.”

Today Ken and I want to explain important aspects of the Twin Prime Conjecture.