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## Recent Questions - Mathematics Stack Exchange most recent 30 from math.stackexchange.com

• Block Matrices Linear algebra
by i9-9980XE on April 6, 2020 at 3:34 am

Suppose $$M = \left(\begin{array}{cc} A & I\\ I & C \end{array}\right)$$ where $A$ is a $p$ x $q$ matrix. What are the dimensions of C? Would $C$ be $p$ x $q$ as well? Someone told me the answer was $q$ x $p$ but I still think that it is $p$ x $q$.

• Weird binomial summation
by Saddy on April 6, 2020 at 3:31 am

My 1st attempt: replacing j with (n-j) So the expression turns out to be S=(sum nnCi)-(sum jnCi) So adding the original and the final expression We get simply S=n* 2^(n-1). My second attempt: considering 3 parts: Part 1: i=j sum {i=j} i*nCi = n*2^(n-1) Part 2: ij they are equivalent So we get 2S Part 3 : taking i=0 to n and j=0to n Which gives (n(n+1)/2 )*2^n Combining all the Parts I get n^2*2^(n-2). But sadly none of my answers match with the given answer. Please someone help me out. I find that i am unable to express my question properly. I would request someone to edit this question .

• Show that map $p$ is continuous
by sedrick on April 6, 2020 at 3:30 am

We have $Y \subset C[0,1]$ be the set of continuous functions on $[0,1]$ which are polynomials of degree $\leq 2$, i.e. $ax^2+bx+c$. Consider map $p:\mathbb{R}^3_\text{usual} \to Y$ mapping $(a,b,c)$ to $f(x) = ax^2+bx+c$ Now we want to show that the maps $p:\mathbb{R}^3_\text{usual} \to Y_{L_1}$ and $p:\mathbb{R}^3_\text{usual} \to Y_{L_\infty}$ are continuous. (Here, $Y_{L_1}$ is the under the $L_1$ topology.) I tried doing $p^{-1}(B(f,\epsilon)) = \{ (a,b,c):\int_0^1 \lvert f(t) - at^2-bt-c \rvert < \epsilon \}$ but I don't know how to proceed.

• MATLAB code for solving fractional order partial differential equation through q-homotopy analysis transform method (q-HATM)
by Fashareena Mohd on April 6, 2020 at 3:28 am

Currently, I'm doing research about fractional order partial differential order and trying to solve it using homotopy analysis method with Laplace transform which is known as q-HATM. Then, solve the equations using MATLAB software but I have searched all the web and couldn't find anywhere. Perhaps someone can help me provide MATLAB code or link to refer? Because this is for my master's thesis.

• Commuting property of normal operator
by ZFR on April 6, 2020 at 3:26 am

Let $V$ be a finite dimensional vector space and $A$ be normal operator on $V$ and $B$ is an operator such that $AB=BA$. Show that $BA^*=A^*B$. I guess that this problem should not be so difficult. I have tried different approaches and I got some identities which do not lead to desired equality. So I would be thankful if you show the solution to this problem, please!

## Bad Science Ben Goldacre's Bad Science column from the Guardian and more...

• Evidence to House of Commons Sci Tech Select Committee on Research Integrity
by Ben Goldacre on December 5, 2017 at 11:42 am

Sorry not to be in regular blogging mode at the moment. Here’s a video of our evidence session to parliament, where they are running an inquiry into research integrity. I think clinical trials are the best possible way to approach this issue. Lots of things in “research integrity” are hard to capture in hard logical

• How do the world’s biggest drug companies compare, in their transparency commitments?
by Ben Goldacre on July 27, 2017 at 6:33 am

Here’s a paper, and associated website, that we launch today: we have assessed, and then ranked, all the biggest drug companies in the world, to compare their public commitments on trials transparency. Regular readers will be familiar with this ongoing battle. In medicine we use the results of clinical trials to make informed treatments about

• Meaningful Transparency Commitments: the WHO Joint Statement from Trial Funders
by Ben Goldacre on July 26, 2017 at 4:17 pm

By now I hope you all know about the ongoing global scandal of clinical trial results being left unpublished, and of course our AllTrials campaign. Doctors, researchers, and patients cannot make truly informed choices about which treatments work best if they don’t have access to all the trial results. Earlier this year, I helped out

• How many epidemiologists does it take to change a lightbulb?
by Ben Goldacre on February 1, 2017 at 12:49 pm

Robin Ince just asked if I know any epidemiologist lightbulb jokes. I wrote this for him. How many epidemiologists does it take to change a lightbulb? We’ve found 12,000 switches hidden around the house. Some of them turn this lightbulb on, some of them don’t; some of them only work sometimes; and some of them

• “Transparency, Beyond Publication Bias”. A video of my super-speedy talk at IJE.
by Ben Goldacre on October 11, 2016 at 8:01 am

People often talk about “trials transparency” as if this means “all trials must be published in an academic journal”. In reality, true transparency goes much further than this. We need Clinical Study Reports, and individual patient data, of course. But we also need the consent forms, so we can see what patients were told. We need

## AnnMaria's Blog Words from the Prez

• Everything is NOT just fine
by annmaria on April 3, 2020 at 10:17 pm

If you think you should be feeling as if everything is fine, STOP IT! Everything is NOT fine. Even if you are healthy and your rent is paid, there is still a pandemic.

• 5 Basics of Consulting Success: Part 1
by annmaria on February 24, 2020 at 1:16 am

Of all the qualities necessary to be a successful statistical consultant, none is more important than communication, even if that communication is only with your future self.

• The one skill a statistical consultant must have
by annmaria on February 17, 2020 at 7:59 pm

There are actually 5 strengths you need to be a successful statistical consultant; communication, testing, statistics (duh), programming and general knowledge outside of your field.

• The first things a statistical consultant needs to know
by annmaria on January 19, 2020 at 7:27 am

I’ll be speaking about being a statistical consultant at SAS Global Forum in D.C. in March/ April. While I will be talking a little bit about factor analysis, repeated measures ANOVA and logistic regression, that is the end of my talk. The first things a statistical consultant should know don’t have much to do with

• From PHPMyAdmin to SAS Studio for lazy people
by annmaria on January 7, 2020 at 2:15 am

You can get data from PHPMyAdmin into SAS Studio with a dozen clicks, even if you know zero SQL.

## Featured Blog Posts - Data Science Central

• Weekly Digest, April 6
by Vincent Granville on April 5, 2020 at 10:30 pm

Monday newsletter published by Data Science Central. Previous editions can be found here. The contribution flagged with a + is our selection for the picture of the week. To subscribe, follow this link.   Featured Resources and Technical…

• Artificial Intelligence strategy for SMEs: A pragmatic approach
by ajit jaokar on April 5, 2020 at 9:09 pm

Background Is an Artificial Intelligence (AI) strategy feasible for SMEs? (Small to Medium Enterprises)? In this post, we present a pragmatic approach for SMEs to consider AI (at low cost) To provide some context - What is AI? - We use the following definitions Machine Learning means…

• Predicting Smart Meters’ Next Non-Communicative Day
by Ramesh on April 2, 2020 at 5:00 am
• Rigett's New Quantum Optimized Compiler
by Robert R. Tucci on April 2, 2020 at 2:30 am

Check out the following paper unveiled last night in ArXiv: An Open-Source, Industrial-Strength Optimizing Compiler for Quantum Programs, by Robert S. Smith, Eric C. Peterson, Mark G. Skilbeck, Erik J. Davis. This is an exciting development for me since I have been a proponent and practitioner of the art of quantum compilers for a long time. The new "optimized quantum compiler" by Rigetti is a computer program that tackles the problem of…

• Little Blue Pearl
by Don Philip Faithful on April 1, 2020 at 8:46 pm

Little Blue Pearl - named after our planet - has kept me occupied for several days during my 14-day Coronavirus isolation. It is fully functional although I suppose it needs a makeover in terms of its appearance. Like a child after summer break, this is going to be my show-and-tell. LBP is designed to…

## New Books and Journals Discussions - AnalyticBridge

• Book: Evaluating Machine Learning Models
by Emmanuelle Rieuf on March 14, 2017 at 6:12 pm

Data science today is a lot like the Wild West: there’s endless opportunity and excitement, but also a lot of chaos and confusion. If you’re new to data science and applied machine learning, evaluating a machine-learning model can seem pretty overwhelming. Now you have help. With this O’Reilly report, machine-learning expert Alice Zheng takes you through the model…

• Book: Python For Dummies
by Emmanuelle Rieuf on August 25, 2016 at 10:50 pm

Python is one of the most powerful, easy-to-read programming languages around, but it does have its limitations. This general purpose, high-level language that can be extended and embedded is a smart option for many programming problems, but a poor solution to others.  Python For Dummies is the quick-and-easy guide to getting…

• Book: Python Machine Learning Blueprints
by Emmanuelle Rieuf on August 24, 2016 at 8:16 pm

Key Features Put machine learning principles into practice to solve real-world problems Get to grips with Python's impressive range of Machine Learning libraries and frameworks From retrieving data from APIs to cleaning and visualization, become more confident at tackling every stage of the data pipeline Book…

• Book: Data Science Essentials in Python
by Emmanuelle Rieuf on August 23, 2016 at 6:10 pm

Go from messy, unstructured artifacts stored in SQL and NoSQL databases to a neat, well-organized dataset with this quick reference for the busy data scientist. Understand text mining, machine learning, and network analysis; process numeric data with the NumPy and Pandas modules; describe and analyze data using statistical and…

• Book: Statistics for Non-Statisticians
by Emmanuelle Rieuf on August 23, 2016 at 1:08 am

Aimed at practitioners The presentation is as non-mathematical as possible Includes many examples of the use of statistical functions in spreadsheets Employs a realistic sample survey as an exemplar throughout the book Fills a gap in the existing literature on…

• Book: Systems Analytics: Adaptive Machine Learning workbook
by Emmanuelle Rieuf on August 10, 2016 at 5:45 pm

SYSTEMS Analytics title refers to a new development effort in the field of Machine Learning grounded firmly in Systems Theory; the subtitle, “ADAPTIVE Machine Learning”, captures the link to the current state of the art. My intention in writing this book is to bring mathematically trained graduates in engineering, physics, mathematics and…

• Book: Superforecasting: The Art and Science of Prediction
by Emmanuelle Rieuf on August 3, 2016 at 11:11 pm

To be published on September 13, 2016; you can pre-order here (\$17.) By Philip Tetlock and Dan Gardner. 352 Pages. Everyone would benefit from seeing further into the future, whether buying stocks, crafting…

• Book: Efficient R Programming
by Emmanuelle Rieuf on July 1, 2016 at 5:37 am

This is the online version of the O’Reilly book: Efficient R programming.  To build the book: Install the latest version of RIf you are using RStudio, make sure that’s up-to-date as well Install the book dependencies.…

• Python Machine Learning
by Emmanuelle Rieuf on June 28, 2016 at 7:01 pm

Unlock deeper insights into Machine Leaning with this vital guide to cutting-edge predictive analytics About This Book Leverage Python's most powerful open-source libraries for deep learning, data wrangling, and data visualization Learn effective strategies and best practices to improve and optimize machine learning systems…

• Book: Effective Data Visualization: The Right Chart for the Right Data
by Emmanuelle Rieuf on June 28, 2016 at 6:38 pm

Written by sought-after speaker, designer, and researcher Stephanie D. H. Evergreen, Effective Data Visualizationshows readers how to create Excel charts and graphs that best communicate data findings. This comprehensive how-to guide functions as a set of blueprints—supported by research and the author’s extensive experience with clients in industries all over the world—for conveying data in an impactful way. Delivered in Evergreen’s humorous and approachable style, the book covers the…