nadavrot

High-Performance Matrix Multiplication

This is a short post that explains how to write a high-performance matrix multiplication program on modern processors. In this tutorial I will use a single core of the Skylake-client CPU with AVX2, but the principles in this post also apply to other processors with different instruction sets (such as AVX512).

Intro

Matrix multiplication is a mathematical operation that defines the product of

lattner

Swift Concurrency Manifesto

Author: Chris Lattner

Chinese Translation by Jason Yu

Contents

• Introduction
• Overall Vision

bennylope

How to Add a Watermark to Video

FFMPEG filters provide a powerful way to programmatically enhance or alter videos, and it’s fairly simple to add a watermark to a video using the overlay filter. The easiest way to install ffmpeg is to download a pre-built binary for your specific platform. Then you don’t have to worry about including and installing all the right dependencies and codecs you will be using.

Once you have ffmpeg installed, adding a watermark is as easy as passing your existing source through an overlay filter like so:

ffmpeg -i test.mp4 -i watermark.png -filter_complex "overlay=10:10" test1.mp4

Basically, we’re passing in the original video, and an overlay image as inputs, then passing it through the filter, and saving the output as test1.mp4.

Ocramius

vendor
composer.lock

kirsteins

var initalArray = [1, 2, 3]
let pointer: UnsafeMutablePointer<Int> = UnsafeMutablePointer(initalArray)
let arrary = Array(UnsafeBufferPointer(start: pointer, count: initalArray.count))

stephenparish

Commit Message Conventions

These rules are adopted from the AngularJS commit conventions.

• Goals
• Generating CHANGELOG.md
  • Recognizing unimportant commits
  • Provide more information when browsing the history
• Format of the commit message
• Subject line

Lurunchik

--partitioning like http://www.postgresql.org/docs/9.3/static/ddl-partitioning.html
--create master table
CREATE TABLE master_table
(
  id serial,
  key character varying NOT NULL,
  value character varying NOT NULL,
  CONSTRAINT master_table_pkey PRIMARY KEY (id)
);
--create slave tables with constraint

DHuckaby

Twitter公式クライアントのコンシューマキー

Twitter for iPhone

Consumer key: IQKbtAYlXLripLGPWd0HUA
Consumer secret: GgDYlkSvaPxGxC4X8liwpUoqKwwr3lCADbz8A7ADU

Twitter for Android

Consumer key: 3nVuSoBZnx6U4vzUxf5w
Consumer secret: Bcs59EFbbsdF6Sl9Ng71smgStWEGwXXKSjYvPVt7qys

Twitter for iPad

Consumer key: CjulERsDeqhhjSme66ECg

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD