## Profile

David Joyner

Works at USNA

Attended Georgia Institute of Technology

Lives in arnold, md

7,737 followers|352,608 views

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### David Joyner

Shared publicly -Who do you write like?

I took different sections of the same story I wrote and got back "James Joyce", "Ian Fleming", "Douglas Adams, "Stephen King", "Dan Brown", and "David Foster Wallace". I have no idea how their algorithm works but it did return the same writer when I took a subsection of text.

I took different sections of the same story I wrote and got back "James Joyce", "Ian Fleming", "Douglas Adams, "Stephen King", "Dan Brown", and "David Foster Wallace". I have no idea how their algorithm works but it did return the same writer when I took a subsection of text.

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I wonder if it does a mean square minimum agains a given vector that is determined from the writer by parsing words and phrases?

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### David Joyner

Shared publicly -Everyone knows they are expected to obey the law, except, it appears, corrupt prosecutors.

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### David Joyner

Shared publicly -For the next time I teach mechanical resonance in DEs:

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### David Joyner

Shared publicly -The site futilitycloset.com (which seems to be down now, or I'd link to the article) ran this:

Pi Without Circles

The sum of the squares of the reciprocals of the positive integers is π2/6.

The sum of their fourth powers is π4/90.

The sum of their sixth powers is π6/945.

The area of the region under the Gaussian curve y = e-x2 is the square root of π.

The probability that two integers chosen at random will have no prime factor in common is 6/π2.

The integer 8 can be written as the sum of two squares of integers, m2 + n2, in four ways, when (m, n) is (2, 2), (2, -2), (-2, 2), or (-2, -2). The integer 7 can’t be written at all as the sum of such squares. Over a very large collection of integers from 1 to n, the average number of ways an integer can be written as the sum of two squares approaches π. Why?"

Isn't the answer to the last question a consequence of the spectral theory of the Laplacian in the plane? Or, is it better to use pure number theory?

Pi Without Circles

The sum of the squares of the reciprocals of the positive integers is π2/6.

The sum of their fourth powers is π4/90.

The sum of their sixth powers is π6/945.

The area of the region under the Gaussian curve y = e-x2 is the square root of π.

The probability that two integers chosen at random will have no prime factor in common is 6/π2.

The integer 8 can be written as the sum of two squares of integers, m2 + n2, in four ways, when (m, n) is (2, 2), (2, -2), (-2, 2), or (-2, -2). The integer 7 can’t be written at all as the sum of such squares. Over a very large collection of integers from 1 to n, the average number of ways an integer can be written as the sum of two squares approaches π. Why?"

Isn't the answer to the last question a consequence of the spectral theory of the Laplacian in the plane? Or, is it better to use pure number theory?

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Alex Fink

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The naive answer to the last question would seem to be that the number of expressions of any integer at most N as a sum of two squares is the number of lattice points inside the disc of radius sqrt(N) in the plane.

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### David Joyner

Shared publicly -A kickstarter project by a friend which I hope gets funded. If you like scifi, you might want to check it out.

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### David Joyner

Shared publicly -Easy but beautiful mate-in-2 chess problem from futilitycloset.com, due to Sam Loyd:

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### David Joyner

Shared publicly -This looks interesting.

Most everyone in the post-production business has heard of HitFilm, the interesting little alternative non-linear editor and effects package from FX Home. In 2013 they completed a successful Kickstarter campaign to bring HitFilm to the Mac. Now they are making plug-ins for that NLE you might already be using that will cost you $499. And NAB 2014 is the perfect place to launch it.

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### David Joyner

Shared publicly -I really like this mate in 2 problem from futilitycloset.com:-)

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2 comments

Nf5 is mate:-)

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### David Joyner

Shared publicly -Extremely cool chess+math problem from the Futility Closet (and Miodrag Petkovic, "Mathematics and Chess"). Very nice problem:-)

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In his circles

2,775 people

Work

Occupation

math prof

Employment

- USNAmath prof, present

Places

Currently

arnold, md

Previously

mountain view, ca - kent, wa - decatur, ga - princeton, nj - san diego, ca

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- Buzz (current)
- stills from a nerdy movie (current)
- Another math blog (current)

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math, writing, tech, edu, ...

Introduction

Enjoy tinkering with mathematics (especially coding theory and representation theory), SAGE (www.sagemath.org) and GAP (www.gap-system.org), writing, computers, video, chess, and photography. Interested in open source and math education-related issues.

Bragging rights

have managed to stay off facebook

Education

- Georgia Institute of Technologymath
- University of Maryland, College Parkmath

Basic Information

Gender

Male

I have used All for the Pet for years and never once had rude service. The store doesn't even open until 9am and Lisa often comes in early to help out people who want to drop off their pet before going to work. I think she does a good job with my pets and her prices are reasonable.

Public - 8 months ago

reviewed 8 months ago