No… These aren’t cinema lenses. They’re auto-focus, still photography lenses. Sigma has just announced three new lenses in their ART line of still-photo lenses: 14mm f/1.8, 135mm f/1.8, and a 24-70mm f/2.8. 480 more words

## Tags » Primes

#### Industrial Strength Left-truncated Prime Checker

I saw a post on Facebook about left-truncatable prime numbers. A left-truncatable prime number is a prime number that is still prime with each successive removal of its left-most digit. 1,016 more words

#### The Next Leader Of Cybertron Is A Total Beast

(Source: kotaku.com)

Earlier this month a Transformer near and dear to my heart faced off against Ultra Magnus, Star Saber and Deathsaurus in a fan vote for who would be the next ‘bot to wield the Matrix of Leadership. 210 more words

#### Games with factorization diagram cards

Since I published a deck of factorization diagram cards last September, a few teachers have picked up copies of the cards and started using them with their students. 524 more words

#### Sharing John Cook's Fibonacci / Prime post with kids

Saw a neat post from John Cook about using a fun fact about the Fibonacci numbers to prove there are an infinite number of primes: 304 more words

#### Sums of Squares and Density

*Lagrange’s Four Square Theorem* (Lagrange, 1770) is the well-known result that every positive integer can be written as the sum of four integer squares. This was strengthened by Legendre’s 1797-1798 proof of the similar-sounding… 1,275 more words

#### Sieve of Eratosthenes (without iteration) in MATLAB

For my CS class there was an extra credit problem in this week’s problem set where we had to write a sieve of Eratosthenes to find prime numbers up to an input integer. 525 more words