# Math

• ## Most Topular Stories

• ### The Mathematics of the Manhattan Project

Math-Blog
8 Jul 2013 | 7:00 am
This article discusses the mathematics of the Manhattan Project which developed the first nuclear reactors and atomic bombs and established high expectations for the effectiveness of mathematical modeling and computer simulations that continue to the present day. It argues that the mathematics used in the Manhattan Project was unusually easy compared to other major inventions and discoveries — which has led to unrealistic and often disappointed expectations for subsequent “New Manhattan Projects.” The Manhattan Project is remarkable in the history of invention and discovery…
• ### Determinant of Matrix (17-11)

CSE Blog - quant, math, computer science puzzles
24 Dec 2013 | 12:53 am
Source: Mailed by Sudeep Kamath (EECS PhD Student, UC Berkeley, EE IITB 2008 Alumnus) Problem:A is a 300 x 300 matrix with 17 on the diagonal, and the rest of the entries being 11. What is det (A) ?
• ### Why do we think P NE NP? (inspired by Scott's post)

Computational Complexity
10 Mar 2014 | 7:55 am
Recently  Scott Posted an excellent essay on reasons to think that P NE NP.  This inspired me to post on the same topic. Inspired is probably the right word. Some of my post is  copied and some of my post   are my thoughts. A good test: if its intelligent and well thought out then its probably from Scott. Why do scientists believe any particular theory?  I state three reasons, though there are likely more: (1) By doing Popperian experiments- experiments that really can fail. Their failure to fail helps to confirm the theory. This is common in Physics, though gets…
• ### Is it divisible by 7? Death by regular expression

7 Jun 2013 | 8:33 am
Here is a fun question at Quora: How does one determine whether a number is evenly divisible by 7? There are some remarkably geeky answers. Those of you who write code might enjoy the second answer, by Anders Kaseorg. Enjoy!
• ### License Plate Math

5 Mar 2014 | 11:38 pm
If you are taking a trip or getting ready for spring break, put those movie players away and have some fun family math time in the car.  There are some great oral math activities that can be done while touring around in your car and I've listed them all right here. Whether you have a 4 year old or a 10 year old, you will find some fun math related ideas to learn while on your trip....Read Full Post
• ## MATH - Google News

• ### Wallace hosts math competition - Dothan Eagle (blog)

11 Mar 2014 | 10:36 am
Wallace hosts math competitionDothan Eagle (blog)Dothan, Ala. – Wallace Community College hosted the 32nd Annual Tri-State Math and Computer Science Olympiad at the Wallace Campus in Dothan on Friday, March 7. Approximately 805 area students and 60 high school instructors from Alabama,
• ### Alan McBride: Advanced math instruction under threat in Northampton - GazetteNET

11 Mar 2014 | 10:23 am
Alan McBride: Advanced math instruction under threat in NorthamptonGazetteNETTwo years ago, Northampton's JFK Middle School eliminated advanced math classes that had been offered for years. At the time, it was expressed that the changes at JFK were designed to allow more students to take advanced math classes when they
• ### Students, faculty decry Penn plan to cut math and science libraries - Philly.com

11 Mar 2014 | 3:55 am
Philly.comStudents, faculty decry Penn plan to cut math and science librariesPhilly.comClockwise from top left, Kevin Shi, Neel Patel, Caitlin Beecham and Brett Frankel are math and grad students that are protesting the closing of their library, the Math/Physics/Astronomy Library in Rittenhouse Labs at University of Pennsylvania
• ### Doing the Math on Polar Sea Ice Melt - Yahoo News

10 Mar 2014 | 2:34 pm
Yahoo NewsDoing the Math on Polar Sea Ice MeltYahoo NewsGolden, a mathematician at the University of Utah, is using math to model the melting of the polar ice caps. He has been on multiple expeditions to the Arctic and Antarctic, where he studies how the microscopic structure of ice affects the large-scale and more »

• ## Search for "math OR mathematics"

• ### Lee Bolsters KCI's Environmental Engineering Capabilities In Houston

11 Mar 2014 | 10:45 am
KCI welcomes Lucia L. Lee, PE, BCEE , to our Houston, Texas, office, as a senior environmental engineer and project manager.
• ### CU-Boulder boasts top-ranked graduate programs

11 Mar 2014 | 10:44 am
Graduate programs across the University of Colorado system again are lauded for excellence in the latest annual rankings from U.S. News & World Report.
• ### Governor Martinez signs 6B state budget 11 Mar 2014 | 10:42 am Governor Susana Martinez signed New Mexico's Fiscal Year 2015 State Budget Tuesday, a bipartisan compromise that enacts several initiatives to increase New Mexico's healthcare workforce, invests in key job creation efforts, and expands education reform initiatives as a means of getting more education dollars into the classroom to help struggling ... (more) • ### Dallas' 14-1 Council System Is a Little Broken, but not Enough To Fix 11 Mar 2014 | 10:41 am Before you pick up that phone to call your council person, imagine him or her taking the call from this chair. • ### Latest SAT overhaul aligns with Common Core 11 Mar 2014 | 10:37 am Administrators in coming years may feel less stressed about adding SAT prep to students' regular coursework. • ## Mathematics News -- ScienceDaily • ### Are you smarter than a 5-year-old? Preschoolers can do algebra 6 Mar 2014 | 10:00 am Millions of high school and college algebra students are united in a shared agony over solving for x and y, and for those to whom the answers don't come easily, it gets worse: Most preschoolers and kindergarteners can do some algebra before even entering a math class. A new study finds that most preschoolers and kindergarteners, or children between 4 and 6, can do basic algebra naturally. • ### Classroom focus on social, emotional skills can lead to academic gains, study shows 6 Mar 2014 | 6:55 am Classroom programs designed to improve elementary school students' social and emotional skills can also increase reading and math achievement, even if academic improvement is not a direct goal of the skills building, according to a study. The benefit holds true for students across a range of socio-economic backgrounds. • ### To teach scientific reproducibility, start young 28 Feb 2014 | 11:01 am In the wake of retraction scandals and studies showing reproducibility rates as low as 10 percent for peer-reviewed articles, the scientific community has focused attention on ways to improve transparency and duplication. A team of math and statistics professors has proposed a way to address one root of that problem: teach and emphasize reproducibility to aspiring scientists, using software that makes the concept feel logical rather than cumbersome. • ### The nature of color: New formula to calculate hue improves accuracy of color analysis 28 Feb 2014 | 11:01 am Color is crucial in ecological studies, playing an important role in studies of flower and fruit development, responses to heat/drought stress, and plant–pollinator communication. But, measuring color variation is difficult, and available formulas sometimes give misleading results. An improved formula to calculate hue (one of three variables characterizing color) has now been developed. • ### Math anxiety factors into understanding genetically modified food messages 27 Feb 2014 | 9:55 am People who feel intimidated by math may be less able to understand messages about genetically modified foods and other health-related information, according to researchers. • ## Scientific American - Math • ### The Math Wars, Lewis Carroll Style 4 Mar 2014 | 5:30 am In 1879, Charles Dodgson, better known as Lewis Carroll, published an odd little book called Euclid and his Modern Rivals (available for free at the Internet Archive). -- Read more on ScientificAmerican.com • ### Equations Are Art inside a Mathematician’s Brain 4 Mar 2014 | 5:00 am A brain area associated with emotional reactions to beauty activates when mathematicians view especially pleasing formulas -- Read more on ScientificAmerican.com • ### A Fluid New Path in Grand Math Challenge 27 Feb 2014 | 12:00 pm A daring speculation offers a potential way forward in one of the great unsolved problems of mathematics: the behavior of the Navier-Stokes equations for fluid flow -- Read more on ScientificAmerican.com • ### The Stunning Symbiosis between Math and Knitting [Slide Show] 24 Feb 2014 | 1:30 pm -- Read more on ScientificAmerican.com • ### The Stunning Symbiosis between Math and Knitting [Slide Show] 24 Feb 2014 | 1:00 pm A meeting of the minds at the intersection of mathematics and fiber arts yields eye-popping creations -- Read more on ScientificAmerican.com • ## NYT > Mathematics • ### A Viable Common Core? 22 Feb 2014 | 9:00 pm Educators and others take part in a national debate over the new learning standards. • ### Ad Infinitum 15 Feb 2014 | 9:00 pm An M.I.T. physicist takes a speculative look at space, time and the possibility of parallel universes. • ### Is the Universe a Simulation? 15 Feb 2014 | 9:00 pm If so, that would help explain some mysterious things about math. • ### In Texting Era, Crisis Hotlines Put Help at Youths’ Fingertips 4 Feb 2014 | 9:00 pm Texting has become such a fundamental way to communicate that crisis groups have begun to adopt it as an alternative way of providing emergency services and counseling. • ### In the End, It All Adds Up to – 1/12 3 Feb 2014 | 9:00 pm A recent video purported to prove that adding an infinite series of natural numbers gives you a smaller answer than you might think, raising compelling questions about the entire notion of infinity. • ## Wild About Math! • ### Chuck Adler – Inspired by Math #33 13 Feb 2014 | 6:27 pm I've admitted before that Physics and I have never gotten along. But, science fiction is something I enjoy. So, when Princeton University Press sent me a copy of Physics Professor Chuck Adler's new book "Wizards, Aliens, and Starships," I was intrigued enough that I wanted to interview the author. This interview rambled, but in a good way. Chuck is a great guest, he's passionate about physics and math as well as fantasy and science fiction. We flowed through a number of subjects and had a grand time. Enjoy! About Chuck Adler Chuck Adler grew up in the DC suburbs, and went to a very good… • ### Martin Gardner undiluted 22 Nov 2013 | 11:54 am Princeton University Press recently published "Undiluted Hocus-Pocus: The Autobiography of Martin Gardner." I've not reviewed the book since these days I pretty much only interview authors and living authors at that. So, no review from me, but I highly recommend Shecky's review and Shecky's first impressions at Math Tango. What inspired to blog this afternoon was an email I received from Andrew S. DeSio, Director of Publicity for Princeton University Press. Andrew has asked me to help spread the word that Martin Gardner really did write his own autobiography. Here's an excerpt from Andrew's… • ### Colm Mulcahy – Inspired by Math #32 21 Sep 2013 | 10:56 am I had the pleasure of interviewing mathematician and mathematical card magic innovator Colm Mulcahy. Dr. Mulcahy just published a book, Mathematical Card Magic: Fifty-Two New Effects. We spent a delightful hour discussing his book, his love of math and magic, and the inspiration behind writing the book. Plus, Dr. Mulcahy shares a few challenges listeners might enjoy chewing on, sprinkled throughout the interview. And, we discuss Martin Gardner, who Colm Mulcahy knew for the last decade of his life and met with several times. You may also enjoy Shecky's text interview with Colm Mulcahy at Math… • ### Kiki Prottsman – Inspired by Math #31 14 Jul 2013 | 7:17 am When I interviewed Ken Fan of Girls' Angle I learned about Kiki and her wonderful work. Kiki is passionate about improving people's relationships to computers, beyond basic literacy to programming and understanding how computers think. While our interview was largely about computers and not math, we both realized that at the core of both is a blend of logical and creative thinking. Kiki's passion for changing experiences, especially those of young girls, is contagious. Listen and tell us if you agree. About Kiki Prottsman Determined to change the face of STEM in a positive way, Kiki is a… • ### Is it divisible by 7? Death by regular expression 7 Jun 2013 | 8:33 am Here is a fun question at Quora: How does one determine whether a number is evenly divisible by 7? There are some remarkably geeky answers. Those of you who write code might enjoy the second answer, by Anders Kaseorg. Enjoy! • ## Loren on the Art of MATLAB • ### Arithmetic Associativity – Not So Fast 26 Feb 2014 | 7:07 am Arithmetic is associative, right? Well, in the world of paper and pencil, where you can often do calculations exactly, that can be true. However, in the computing world, where real numbers can't always be represented exactly because of working with finite precision datatypes, it turns out that you can't depend on the arithmetic to behave the way you were taught in grade school.ContentsLet's Do Some MathLet's Try Another ExampleHave You Rewritten Expressions to Get Better Accuracy?Let's Do Some MathSuppose I want to check the following:$$\sqrt {2} = 2/\sqrt {2}$$I can do this analytically… • ### Double Integration in MATLAB – Methods and Handling Discontinuities, Singularities, and More 12 Feb 2014 | 7:06 am In our recent post, Mike Hosea and I talked about adjusting both the absolute and relative tolerances for getting more accurate results when calculating a double integral. Today we'd like to talk about choosing the method of integration as well as which order to choose for the first dimension (direction) of integration.ContentsSet the StageChanging the Order of IntegrationSingularitiesCan You Take Advantage of these New Integration Routines?Set the Stageintegral2 has, at present, two different integration methods, 'tiled' and 'iterated', not counting the 'auto' method that chooses between… • ### Coding Best Practices – A Good Read 29 Jan 2014 | 7:05 am Coding Best Practices - A Good ReadI have written blogs before on coding best practices in MATLAB and they have always generated a lot of great feedback. I recently came across a language-neutral list of best practices for scientific computing, written by Greg Wilson of Software Carpentry.If you don't want to start by reading the whole article, I strongly encourage you to read Greg's summary. He breaks the practices into eight categories. I have to say, I think they are very well stated, starting with "Write programs for people, not computers.".I have to say, I think Greg hit the nail on the… • ### Cool Graphics and Graphical User Interfaces 15 Jan 2014 | 8:15 am Today, David Garrison and Sarah Wait Zaranek, today's guest bloggers, would like to ask for your help in tracking down interesting examples using MATLAB graphics and UI building capabilties.ContentsLooking For Your Graphics and GUIsSome Examples of Interesting Graphics and GUIsFor Those New to Making Graphics in MATLABConclusion (or How to Send Us Your Examples)Looking For Your Graphics and GUIsWe are always looking for interesting MATLAB code. Your examples help us understand all the things people do in MATLAB and they help us plan for future enhancements. With that in mind, we'd like to ask… • ### Seeking Symmetry in MATLAB 8 Jan 2014 | 6:27 am Sometimes I need to construct a matrix with certain symmetries. There are a bunch of tools in MATLAB that are well suited for such tasks. In today's post, I will mention the ones I use most often.ContentsPerhaps the Most Ignored Functionality For SymmetryVector SymmetrySome Other Tools to Help SymmetrizeDoes Your Work Require Symmetry?Perhaps the Most Ignored Functionality For SymmetryI want to start with perhaps the most ignored funtionality for ensuring symmetry of a certain kind is the transpose operators (ctranspose) and (transpose). The reason these can be so so helpful is that during… • ## Homeschool Math Blog • ### Common Core and common sense 10 Mar 2014 | 2:22 pm I wrote somewhat of a long piece about Math Mammoth's position concerning the Common Core Standards, and some bad examples of supposed "common core math" or "new math" as some call it.Math Mammoth and the Common Core StandardsI hope it is helpful to at least some of you. • ### Finding a total when the fractional part is known 9 Mar 2014 | 8:28 am Someone asked me recently, I have had great success with the Grade 4 Light Blue Series with my twin daughters and we have been breezing through the curriculum. ... For the most part, they get how to find the fractional part but we did have some trouble on problems 4 on page 59 Worktext 4-B and problem 7 on page 60 in Worktext 4-B. They have to do with finding the total number of something when you are given a fractional part. I had a hard time teaching the concept of "working backwards" and was wondering if you have any additional resources or problems we could use to practice.Working… • ### Reminder... math puzzles contest 26 Feb 2014 | 12:51 pm You have till February 28, 2014 to take part in my MATH PUZZLES CONTEST. Please read the details at http://homeschoolmath.blogspot.com/2014/02/contest-looking-for-math-puzzles.html Every participant will be entered into a random drawing of Math Mammoth Blue Series books!3 people will receive25 worth  of Blue Series books of their choosing3 people will receive $15 worth of Blue Series books of their choosingHave fun! • ### Homeschool science resources 25 Feb 2014 | 4:05 am Some people have asked me what science curricula and resources I use and recommend. I made a page about them, with a short review of each:Homeschool science resources Basically, I have used regular textbooks as a "spine" since they are so affordable, and supplemented that with videos and activities from various sources. • ### From frustration to exuberance! - Math Moment Story 19 Feb 2014 | 1:10 pm This is one of the stories sent to my recent Math Moment(s) contest.I was one of those people who feared math their entire lives and I was afraid that somehow I would pass it on to my daughter. It was always the same with our math sessions. We would be both excited at first but then somewhere along the way things would start to go downhill and we both end up in frustration. There was this day when my daughter was in tears at the end of our session. We didn't do math for a while after that incident as I was sure that I finally killed math for her for good. When we started again, it was met… • ## About.com Mathematics • ### Testing Mom 10 Mar 2014 | 12:02 am Are you looking for samples of both standardized and non standardized tests in Math? At TestingMom.com, you will find just that. If you or your child is going to take a test that has a math component to it, Testing Mom has practice math questions for that test and it is modeled after the questions on that test....Read Full Post • ### License Plate Math 5 Mar 2014 | 11:38 pm If you are taking a trip or getting ready for spring break, put those movie players away and have some fun family math time in the car. There are some great oral math activities that can be done while touring around in your car and I've listed them all right here. Whether you have a 4 year old or a 10 year old, you will find some fun math related ideas to learn while on your trip....Read Full Post • ### 101 on Inequalities 27 Feb 2014 | 2:01 am The concept of inequalities is taught in pre algebra and then re-visisted throughout algebra. The early entry of the greater than or less than symbols () starts as early as the second grade. This week's article is the 101 on inequalities and gives a very basic overview and introduction to inequalities. See also: How to Graph Inequalities How to Solve and Graph Inequalities Involving Multiplication and Division • ### Improve Your Math Scores in 7 Sensible Steps 24 Feb 2014 | 10:44 am Math is not a spectator sport. To improve in math, you must do math and isn't that just like many things in life? If you want to play an instrument, you practice. If you want to do well in a sport, you practice. Math isn't any different in this regard. The math you do is for you, it's not for your teacher, after all, your teacher already knows the math. This article gives you 7 sensible steps to improve your scores in math. • ### Are you a Math Phobic? 20 Feb 2014 | 12:33 pm If you answered yes to this question, this article is for you. I ask you, how or why did you become a math phobic? Chances are you will respond with, I just don't understand math or that I just never had anyone that would explain math the way I learn math. Unfortunately, you weren't told that everyone given the appropriate time and support can do math. Hopefully, with a positive attitude and a caring tutor, parent or teacher, you will combat the math phobia and move forward positively....Read Full Post • ## Let's Play Math! • ### Education Bloggers: Share Your Post! 11 Mar 2014 | 5:02 am photo by Omar Omar via flickr If you are a homeschooler or classroom teacher, student or independent learner, or anyone else who writes about math, now is the time to send in your favorite blog post for next week’s Math Teachers at Play (MTaP) math education blog carnival. Click here to submit your blog post. Browse all the past editions of the Math Teachers at Play blog carnival Don’t procrastinate: The deadline for entries is this Friday. The carnival will be posted next week at Christy’s Houseful of Chaos. If you haven’t written anything about math lately, here are… • ### Pi Day Roundup 7 Mar 2014 | 2:56 am [Feature photo above by Nicolo' Canali De Rossi.] Math holiday alert: March 14th is Pi Day! Here are some ideas to help you celebrate… Pi Day Posts on Let’s Play Math! Blog Happy Pi Day I Happy Pi Day II Happy Pi Day III: Visualizing Pi Poetry for Pi Day Do the Digits of Pi Encode Shakespeare’s Plays? Egyptian Math: Pi And Did You Know? Pi Day is also Albert Einstein’s birthday. Happy Birthday, Einstein! Happy Birthday, Einstein (Part 2) Happy Birthday, Einstein (Part 3) Happy Birthday, Einstein (Part 4) A Pinch of Pi Day Humor For Pi Day, Pi equals Four? Humble pi Pi… • ### Reblog: The Case of the Mysterious Story Problem 5 Mar 2014 | 5:38 am [Feature photo above by Carla216 via flickr (CC BY 2.0).] Here’s a blast from the Let’s Play Math! blog archives: Seven years ago, I blogged a revision of the first article I ever wrote about homeschooling math. I can’t even remember when the original article was published — years before the original (out of print) editions of my math books. I hope you enjoy… The Case of the Mysterious Story Problem I love story problems. Like a detective, I enjoy sifting out clues and solving the mystery. But what do you do when you come across a real stumper? Acting out story… • ### Improper Fractions: A Mathematical Trauma 25 Feb 2014 | 4:46 am Feature photo (above) by Jimmie via flickr. Here’s a blast from the Let’s Play Math! blog archives: My 8-year-old daughter’s first encounter with improper fractions… Photo (right) by Old Shoe Woman via Flickr. Nearing the end of Miquon Blue today, my youngest daughter encountered fractions greater than one. She collapsed on the floor of my bedroom in tears. The worksheet started innocently enough: [Click here to go read the original post.] Don’t miss any of “Let’s Play Math!”: Subscribe in a reader, or get updates by Email. • ### Math Is Like Ice Cream 19 Feb 2014 | 8:35 am Wednesday Wisdom features a quote to inspire my fellow homeschoolers and math education peeps. Today’s quote is from my About page. Background courtesy of Pinstamatic. Get all our new math tips and games: Subscribe in a reader, or get updates by Email. • ## Basic mathematics blog • ### Factoring formulas 25 Feb 2014 | 7:56 am You can find here a comprehensive list of commonly used factoring formulas. • ### Math constants 24 Feb 2014 | 2:19 pm You can find here a comprehensive list of commonly used math constants. • ### Online educational videos 31 Jan 2014 | 10:25 am Online educational videos for teachers and students. Become a better teacher. Help students achieve their full potential • ### Math Homework 12 Nov 2013 | 6:12 pm 1)A recipe needs 3/4 teaspoon black pepper and 1/4 red pepper. How much more black pepper does the recipe need? Solution: 3/4 - 1/4 = 2/4 = 1/2 The recipe • ### ALGEBRA II 28 Oct 2013 | 8:54 am FIND THE VALUE OF K SO THAT THE TWO GIVEN LINES WILL BE PARALLEL. 3X-KY=7 2X+5Y=-1 First, put the two equations in standard form 3X - KY = 7 3X - 7 • ## ChapterZero • ### Decision time: MacPorts vs Homebrew vs Fink 7 Mar 2014 | 8:12 pm My work macbook pro recently crapped out on me during an update of the OS (apparently something has a tendency to go wrong with the video card or its driver or something similar during this particular update for this particular model … sigh) so I’ve had the joy of reinstalling my personal ecosystem of software again. One of the crucial decisions for me is whether to use MacPorts, HomeBrew, or Fink to allow me to manage the installation of non-trivial Unix packages. This post is really just to remind myself that at this go-round, I chose MacPorts because of these posts. • ### Adagrad and projections onto ellipsoids 6 Feb 2014 | 10:16 pm ((Caveat! I am not sure the manipulations done in this post are correct, but the gist is certainly there.)) One of my favorite optimization techniques is Adagrad, a first-order technique that approximates the Hessian by using all the gradients up to that point. It calls for updates of the form: $x_{t+1} = \Pi_{\mathcal{X}}^{G_t^{1/2}} (x_t - \eta G_{t}^{-1/2} g_t),$ or more practically for high-dimensional problems, $x_{t+1} = \Pi_{\mathcal{X}}^{\text{diag}(G_t)^{1/2}} (x_t - \eta \text{diag}(G_{t})^{-1/2} g_t).$ Here, $$g_t$$ denotes the gradient at step $$t$$, $$\eta$$ is a fixed… • ### Back of the envelope calculations of how fast your computer can do linear algebra operations 23 Jan 2014 | 3:28 pm Let’s talk about CPU speed, practically. By practically, I mean, how fast can your CPU do linear algebra operations. And by linear algebra operations, I mean matrix-matrix multiplies. First, you need to calculate how many FLOPS your computer can do. The following formula comes in handy: $\text{nFLOPS} = \text{cores} \cdot \frac{\text{clock cycles}}{\text{second}} \cdot \frac{\text{FLOPS}}{\text{cycle}}.$ You probably already know the number of cores in your computer, and the number of clock cyles. The interesting thing here is the number of FLOPS per cycle: this depends on the… • ### A useful trick for computing gradients w.r.t. matrix arguments, with some examples 12 Nov 2013 | 7:56 pm I’ve spent hours this week and last week computing, recomputing, and checking expressions for matrix gradients of functions. It turns out that except in the simplest of cases, the most painfree method for finding such gradients is to use the Frechet derivative (this is one of the few concrete benefits I derived from the differential geometry course I took back in grad school). Remember that the Frechet derivative of a function $$f : X \rightarrow \mathbb{R}$$ at a point $$x$$ is defined as the unique linear operator $$d$$ that is tangent to $$f$$ at $$x$$, i.e. that satisfies \[ f(x+h)… • ### A workaround for installing SQBLib 10 Oct 2013 | 12:54 pm I spent about an hour today getting Carlos Becker’s SQBLib package for gradient boosted tree regression in matlab working. The issue is that it depends on liblbfgs, and following the instruction Carlos gave for compiling liblbfgs resulted in errors when MATLAB tried to link liblbfgs into his code. Specifically, I got a mysterious error like /usr/bin/ld: /home/agittens/Downloads/liblbfgs-1.10/lib/lbfgs.o: relocation R_X86_64_32S against .text' can not be used when making a shared object; recompile with -fPIC. See the original install instructions. Here’s the fix that worked for me… • ## Computational Complexity • ### Why do we think P NE NP? (inspired by Scott's post) 10 Mar 2014 | 7:55 am Recently Scott Posted an excellent essay on reasons to think that P NE NP. This inspired me to post on the same topic. Inspired is probably the right word. Some of my post is copied and some of my post are my thoughts. A good test: if its intelligent and well thought out then its probably from Scott. Why do scientists believe any particular theory? I state three reasons, though there are likely more: (1) By doing Popperian experiments- experiments that really can fail. Their failure to fail helps to confirm the theory. This is common in Physics, though gets… • ### Favorite Theorems: Unique Games 6 Mar 2014 | 4:40 am Michel Goemans and David Williamson made a splash in the 90's using semidefinite programming to give a new approximation algorithm for the max-cut problem, a ratio of 2θ/(π(1-cos(θ)) minimized over θ between 0 and π, approximately 0.87856. Hard to believe that this ratio is tight, but it is assuming the unique games conjecture. Optimal Inapproximability Results for MAX‐CUT and Other 2‐Variable CSPs? by Subhash Khot, Guy Kindler, Elchanan Mossel and Ryan O’Donnell Noise stability of functions with low influences: Invariance and optimality by Elchanan Mossel, Ryan O’Donnell… • ### Why are there so few intemediary problems in Complexity? In Computability? 4 Mar 2014 | 8:07 am There are thousands of natural PC problems. Assuming P NE NP how many natural problems are there that are in NP-P but are NOT NPC? Some candidates are Factoring, Discrete Log, Graph Isom, some in group theory, and any natural sparse set. See here for some more. A student asked me WHY there are so few natural intermediary problems. I don't know but here are some options: Bill you moron, there are MANY such problems. You didn't mention THESE problems (Followed by a list of problems that few people have heard of but seem to be intermediary.) This is a question of Philosophy and hence not… • ### Why Become a Professor 27 Feb 2014 | 5:18 am Someone took me to task because in November I posted that the CRA News had 50 pages of job ads but didn't note that very few of those ads specifically were searching for CS theory faculty. Yes, it is true that theory is not as high on the search agenda as big data and other applied areas, but many of these schools will hire theorists after they fail to find qualified applicants in the other areas. My advice is to apply widely and it's not too late to do so, as many CS departments are just starting their interview process. Why is it so hard for universities to hire in applied CS? Because you… • ### When is a paper public? When is anything public? 23 Feb 2014 | 2:33 pm A while back I had a paper in an intermediary stage. The version posted to my Ramsey Theory Course Website was not final. Is the paper public? I didn't think about it much but I didn't intend it to be since it was not done yet. But Adam Sheffer's Google Scholar (more on that later) didn't know that. So his Google Scholar program found the paper and he blogged about it here. This was FINE- my co-author David Conlon posted a comment on the blog that a revised version was coming, and I asked Adam to modify the blog to say so as well. Plus, I am DELIGHTED and SURPRISED when someone noticed my… • ## Mathematics and Computation • ### Intuitionistic Mathematics and Realizability in the Physical World 4 Mar 2014 | 7:57 am This is a draft version of my contribution to “A Computable Universe: Understanding and Exploring Nature as Computation”, edited by Hector Zenil. Consider it a teaser for the rest of the book, which contains papers by an impressive list of authors. Abstract: Intuitionistic mathematics perceives subtle variations in meaning where classical mathematics asserts equivalence, and permits geometrically and computationally motivated axioms that classical mathematics prohibits. It is therefore well-suited as a logical foundation on which questions about computability in the real world… • ### Univalent foundations subsume classical mathematics 13 Jan 2014 | 9:10 am A discussion on the homotopytypetheory mailing list prompted me to write this short note. Apparently a mistaken belief has gone viral among certain mathematicians that Univalent foundations is somehow limited to constructive mathematics. This is false. Let me be perfectly clear: Univalent foundations subsume classical mathematics! The next time you hear someone having doubts about this point, please refer them to this post. A more detailed explanation follows. In standard mathematics we take classical logic and set theory as a foundation:$\text{logic} + \text{sets}$On top of this we build… • ### Costa’s minimal surface with PovRay 30 Dec 2013 | 8:40 am A student of mine worked on a project to produce beautiful pictures of Costa’s minimal surface with the PovRay ray tracer. For this purpose she needed to triangulate the and compute normals to it at the vertices. It is not too hard to do the latter part, and the Internet offers several ways of doing it, but the normals are a bit tricky. If anyone can calculate them with paper and pencil I’d like to hear about it. I went back to my undergraduate days when I actually did differential geometry and churned out the normals with Mathematica. It took a bit of work, kind advice from my… • ### The elements of an inductive type 28 Aug 2013 | 7:13 am In the HoTT book issue 460 a question by gluttonousGrandma (where do people get these nicknames?) once more exposed a common misunderstanding that we tried to explain in section 5.8 of the book (many thanks to Bas Spitters for putting the book into Google Books so now we can link to particular pages). Apparently the following belief is widely spread, and I admit to holding it a couple of years ago: An inductive type contains exactly those elements that we obtain by repeatedly using the constructors. If you believe the above statement you should keep reading. I am going to convince you that… • ### How to review formalized mathematics 19 Aug 2013 | 5:10 am Recently I reviewed a paper in which most proofs were done in a proof assistant. Yes, the machine guaranteed that the proofs were correct, but I still had to make sure that the authors correctly formulated their definitions and theorems, that the code did not contain hidden assumptions, that there were no unfinished proofs, and so on. In a typical situation an author submits a paper accompanied with some source code which contains the formalized parts of the work. Sometimes the code is enclosed with the paper, and sometimes it is available for download somewhere. It is easy to ignore the… • ## Natural Blogarithms • ### How to Insert Equation Numbers in Word 2010 3 Mar 2014 | 10:46 am How to Insert Equation Numbers in Word 2010. In most cases, I’m using LaTEX to typeset my math docs but when I am in a hurry or I’m having my students write up reports, I need to use Word. Here’s a quick demo for adding equation numbers in word that auto-number and can be referenced in the text. • ### Graphs of Sine and Cosine Functions 3 Mar 2014 | 7:52 am I just posted a new video to the Trigonometry Lecture Series. This is the 11th in the series. In this video, I cover how to identify properties of sine and cosine graphs, determine the amplitude and period of sinusoidal functions, graph the sinusoidal functions using key points, and find an equation for a sinusoidal graph. View on YouTube • ### How to Insert an Excel Chart into a Blackboard Discussion Board 2 Mar 2014 | 8:44 pm • ### New Videos in the Trigonometry Video Series 10 Feb 2014 | 5:46 pm Just finished uploading five new videos to my online video lecture series in Trigonometry. Here’s the first and a link to the playlist on YouTube: Link to Full Playlist Newly added: Lecture 6: Measuring Angles in Radians Lecture 7: Definition of Trigonometric Functions Lecture 8: Trig Values of Special Families of Angles Lecture 9: Properties of Trig Functions Lecture 10: Basic Identities of Trig Functions • ### Peer Instruction (almost) always trumps the “Great Math Performer” 3 Feb 2014 | 9:22 am (Submitted as an essay in the MOOC – “History and Future of (Mostly) Higher Education” on Coursera) For the first several years teaching in the undergraduate mathematics classroom, I was convinced that the better my lecture, the better the learning that took place in my Math classes. I was extremely enthusiastic of my presentation of factoring polynomial or row-reducing large matrices, and almost any other math topic you can conceive. I worked hard to provide visually stimulating examples and always received high marks on my student evaluations. And yet, there was no… • ## mathematics « WordPress.com Tag Feed • ### NEW BOOK!! The Improbability Principle 8 Mar 2014 | 8:53 pm NEW BOOK!! The Improbability Principle: Why Coincidences, Miracles, and Rare Events Happen Every Day by David J Hand (Senior Research Investigator and Emeritus Professor of Mathematics at Imperial College, London) • ### Converting from One Coordinate System to Another 8 Mar 2014 | 8:08 pm Given: ~The following rectangular (Cartesian) coordinates are given: (-2√3 , 2) Problem: ~ Convert these coordinates to Polar Coordinate form. Extra Notes: ~ Using a unit circle and a reference triangle may be helpful in solving this problem. ____________________________________________________________________________________________________ Do you have an answer that you want to share? Be sure to click “Leave a Comment” below to post your suggestions. If you would like more ‘thought-provoking’ problems, please check back weekly for new updates. Thanks for visiting and… • ### Peirce's 1870 “Logic Of Relatives” • Comment 9.7 8 Mar 2014 | 7:00 pm From this point forward we may think of idempotents, selectives, and zero-one diagonal matrices as being roughly equivalent notions. The only reason I say roughly is that we are comparing ideas at different levels of abstraction in proposing these connections. We have covered the way that Peirce uses his invention of the comma modifier to assimilate boolean multiplication, logical conjunction, and what we may think of as serial selection under his more general account of relative multiplication. But the comma functor has its application to relative terms of any arity, not just the zeroth… • ### How to use Unicode in LaTeX (by LuaTeX or XeTeX) 8 Mar 2014 | 4:44 pm Table of Contents before we begin LuaLaTeX vs XeLaTeX and what are they? first example how to experiment with adjusting font features in summary something about LuaLaTeX The goal of this post is to gradually build up minimal examples for making Unicode text work in LaTeX documents by using LuaTeX or XeTeX. In the end, we will have produced PDF files containing CJK text (Chinese, Japanese, Korean or hangul text). 1. before we begin To make things simple, I will assume your goal is to be able to write LaTeX documents with Japanese or Korean text in them. Before we begin, there are four things… • ### all numbers are interesting! 8 Mar 2014 | 4:20 pm Due to the amount of work I have in recent months or may be in couple coming months, I won’t have the time to type up what I have in my head at the moment. I do have a few articles in my mind. Maybe wait till this summer… Anyway, here is a statement: All numbers are interesting. Proof. (by contradiction) Suppose there exists an uninteresting number, but that by itself is interesting. Therefore all numbers are interesting. • ## MathNotations • ### 4% of 8% of 16x is what % of 2x? New SAT, Common Core and Percents, Pt.1 8 Mar 2014 | 9:37 am A classic SAT math challenge that will probably not go away on the new SAT coming in 2016. And just imagine if calculators are not allowed for this! Watch "4% of 8% of 16x is what % of 2x? New SAT, Common Core and Percents Pt 1" on YouTube - https://www.youtube.com/watch?v=WY58ebnZvCI&feature=youtube_gdata_player VISIT ME DAILY ON TWITTER AT twitter.com/dmarain • ### Similar Figures MathCast - The Big Ideas and the Common Core 4 Mar 2014 | 5:36 am Watch "Similar Figures - The Big Ideas and the Common Core" on YouTube - https://www.youtube.com/watch?v=TOTGf7HvC0A&feature=youtube_gdata_player This 20 min video develops the Basic Proportionality Theorems re perimeters and areas of similar figures. Multiple representations and teaching conceptually are demonstrated with a strong emphasis on visualization. Feedback would be helpful and appreciated... VISIT ME DAILY ON TWITTER AT twitter.com/dmarain • ### |5x-17| less than 2x-1: Abs Value Ineq and the Common Core 2 Mar 2014 | 10:48 am Watch "|5x-17| less than 2x-1 Abs Values and Common Core" on YouTube - https://www.youtube.com/watch?v=xoi5G85WviY&feature=youtube_gdata_player VISIT ME DAILY ON TWITTER AT twitter.com/dmarain • ### 70a+19b=2838 SATs, Algebra, Number Sense and the Common Core 20 Feb 2014 | 2:25 pm Click on link below to view video on YouTube. At this time I'm not embedding these videos in my blog. Pls let me know if these screencasts are viewable on your desktop, laptop, tablet or phone. For now they have to be viewed in Portrait mode. The video quality is limited by my hardware and software at this time so the resolution is probably only fair. Also any suggestions for improvement would be appreciated. If there's a particular problem or topic for which you'd like me to make a screencast let me know that as well. • ### Common Core SAT-type Quadratic Function Challenge Screencast 18 Feb 2014 | 8:06 am Tired of this yet? Well, the novelty of this screencast technology hasn't worn off yet for me! One of my SAT students requested more practice with Quadratic Functions and coordinate problems so here it is... Watch "SAT-Type Quadratic Functions Challenge Problem" on YouTube - https://www.youtube.com/watch?v=nb-eqlUNn4Y&feature=youtube_gdata_player VISIT ME DAILY ON TWITTER AT twitter.com/dmarain • ## Institute for Mathematics and Computer Science • ### IMACS Math Academy for Broward County Middle School Students 19 Feb 2014 | 10:00 pm The IMACS Math Academy is an intensive one-week program for exceptional students currently attending middle school in Broward County, Florida. Broward County, Florida students currently attending grades 6-8 are invited to apply to the IMACS Math Academy, an intensive one-week program designed to stimulate talented students’ interest in mathematics beyond the traditional classroom. There is no cost to attend the IMACS Math Academy! There are two scheduled sessions. The first will be held March 24 – 28 during Spring Break. The second will be held June 23 – June 27 during… • ### AP Computer Science … Updating 29 Jan 2014 | 10:00 pm Following a recent review of the AP Computer Science A course and exam, the College Board has decided to replace its case study requirement with a requirement to complete a minimum of 20 hours of hands-on lab experiences. This change, which will take effect for the 2014-2015 school year, is being implemented to more effectively support student learning of core concepts in computer science. IMACS continues to follow closely all communications from the College Board, as well as discussions within the APCS community, on the forthcoming changes and will act accordingly. From the beginning,… • ### Letters to a Young Math Teacher 1 Jan 2014 | 10:00 pm The following letter is extracted from the new book, Letters to a Young Math Teacher, by Gerald Rising and Ray Patenaude, which is available from Amazon.com and other sources. Gerry Rising is Distinguished Teaching Professor Emeritus at State University of New York at Buffalo where he co-founded the university’s Gifted Math Program for highly-qualified regional students in grades seven through twelve. Gerry Rising was for many years associated with IMACS activities and is a strong supporter of our work. Letter Seventeen: A Bag of Tricks Paul Rosenbloom enjoyed an international… • ### Driven to Abstraction: Strengthen Your Thinking Skills with Computer Science 4 Dec 2013 | 10:00 pm IMACS is proud to be a Partner for CSEdWeek, December 9-15, 2013. Have you registered for the Hour of Code? Do it now! Abstract reasoning ability entered the national conversation this year as the Common Core State Standards in mathematics were broadly implemented in the United States. In particular, one of the eight Standards for Mathematical Practice is to “reason abstractly and quantitatively.” The so-called STEM subjects — science, technology, engineering and math — are well-known for emphasizing this skill. Given that STEM-related fields are where most… • ### Thanksgiving Wishes from IMACS 27 Nov 2013 | 10:00 pm Image: freepik.com IMACS hopes this Thanksgiving day finds you with much to be thankful for as you enjoy the company of friends and loved ones. To our students, parents, instructors, staff and partner schools — you have our deepest appreciation for making this another fun-filled year of learning and achievement! The IMACS Blog will return next Thursday, December 5, with a regular feature article. Happy Thanksgiving! Give the gift of an IMACS education! Enroll your child in our gifted math and online computer science courses. Like IMACS on Facebook to get weekly IMACS logic puzzles. • ## mathrecreation • ### another iteration of squares 24 Feb 2014 | 6:39 pm more playing around with GSP, like this post. • ### art for maths sake 9 Jan 2014 | 7:26 pm "Let none be ashamed to learn, for a good work requireth good counsel."- Albrecht Dürer, 1520Mathematics and Art, sometimes thought to be opposite poles of human experience and activity, can sometimes sit down together in conversation.Sometimes we might think of the conversation as more of a lecture - with Mathematics providing some technical advice. Perspective drawing is the prime example - where mathematics allows artists to create realistic images, or else to subvert the expectations of realism (as in anamorphic art). Art does reply - for these mathematical tools, it repays the… • ### brain curve 18 Dec 2013 | 7:28 pm This closed curve looks a bit like a lateral slice of a cerebral cortex, and has a very simple parametric formula:If you let n = 0, the curve is a circle, for n = 1, you get an epicycloid, and for n around 4 you start to get something that looks like the brain slice. I think that there is a small copy of the whole curve on the left, giving the curve some self-similarity.I first saw this curve, and some other neat ones that have very similar formulas, when looking at the scrambler amusement park ride (see here, and here).Update: A very nice Mathematica animation that traces out this curve can… • ### euler spirals in Fathom and TinkerPlots 26 Nov 2013 | 7:07 pm A nice post on mathen inspired me to construct some Euler spirals using Fathom and Tinkerplots. I like using these tools for this sort of playing around - they are intended for middle and high-school data management activities, but are, effectively, simple quasi-programming environments. The results are not as pretty as those from mathen, but are nice enough and very easy to generate.To recreate images like these in either Fathom or Tinkerplots you need two sliders - I called them magnitude and delta.You then create a collection (or card set in TP) with four attributes (n, x, y, and theta). • ### snowflake construction in GSP 19 Nov 2013 | 7:30 pm Here are instructions for making a snowflake iteration similar to the one shown in the previous post using Geometer's Sketchpad. I generally don't put useful things like instructions on this blog, but I thought I would make an exception: these fun and easy constructions are worth doing because they are pretty, and they illustrate some important concepts associated with recursion. GSP is a great tool for playing with these sorts of things - I haven't explored Geogebra at all, so I can't comment on what similar sorts of things can be done with that tool.1. Draw a line segment AB (using the… • ## Math-Blog • ### STEM Shortage Claims and Facebook’s$19 Billion Acquisition of WhatsApp

10 Mar 2014 | 5:42 am
• ## PlainMath.net

• ### Divisibility Rules: Quantitative Aptitude Section

8 Mar 2014 | 3:42 am
There are some specific rules by which we can determine the divisor of the given number. Today I will discuss divisibility rules from 2 to 19. Using these rules you can easily determine a divisor of given number, however large it may be. Let me tell you the rules of divisibility from 2 to 19.Divisibility Rules  Divisibility by 2Number which ends with even number or 0 is always divisible by 2.For Example: 44, 120, 56, 70 etc are divisible by 2.23, 57, 79 etc are not divisible by 3.Divisibility by 3For a given number, if sum of ts digits is divisible by 3, then the number will be divisible…
• ### Combinations

1 Mar 2014 | 1:00 am
Unlike a permutation, in a combination the order of the objects selected does not matter. For example, if you were choosing a team of three students from a class of ten, the order you said "Joe, Sally, John" would not matter to who is in the group- saying "Sally, Joe, John" instead doesn't change anything.How to solve a combinationThe number of ways you can make a combination of r objects out of a set of n objects is made from the formula below:C=n!/r!(n-r)!An ExplanationYou may be asking (like I did when I learned this material), "What? That formula doesn't make sense!".- However, it is…
• ### Permutations

1 Mar 2014 | 1:00 am
Permutations are very important in Quantitative Aptitude. They are most often used for finding probabilities or the number of ways something can be arranged. In fact, a permutation is simply the number of different ways a set can be arranged.An Example of a PermutationOne of the most used examples of a permutation is the number of ways to arrange a batting order for a baseball team.Example1:  A baseball team has 9 players, each of which go up and bat before repeating the order. How many different ways can you organize 9 players in an order?Solution: For the first position, there would be…
• ### Simple or linear Equations: Tricks and Examples.

28 Feb 2014 | 6:17 am
I have already discussed a concept - Quadratic Equations. Today I will discuss some examples of simple equations which have been proved to be a very important topic for various competitive exams. The problems of linear equations can be easily solved by using simple tricks. Lets discuss how.Examples with solutionsExample1: If 3x + 6 = 4x - 2, then find the value of x?1. 82. 43. 64. 7Solution: 3x + 6 = 4x-24x - 3x = 6 + 2 x = 8`By using trick: This question can be easily solved by eliminating the options.Firstly check option(1) whether it satisfies the equation or…
• ### Geometry (Part-2) for SSC CGL Tier-I

23 Feb 2014 | 1:55 am
In my previous session of Geometry, I discussed some properties of triangles. Also, I shared some important questions for SSC CGL. Today I'm going to discuss congruency and similarity of triangles which are one of the most important properties of triangles. There are some rules to determine whether the given two triangles are congruent or similar or nothing. Lets discuss it one by one.Congruency of TrianglesTwo triangles are said to congruent ifthey overlap each other when placed one over the other.they have same area.identical in all aspects. When two triangles are congruent?Now, the…