Lukas steinelu

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

HTTP Streaming (or Chunked vs Store & Forward)

The standard way of understanding the HTTP protocol is via the request reply pattern. Each HTTP transaction consists of a finitely bounded HTTP request and a finitely bounded HTTP response.

However it's also possible for both parts of an HTTP 1.1 transaction to stream their possibly infinitely bounded data. The advantages is that the sender can send data that is beyond the sender's memory limit, and the receiver can act on

Download Only Certain File Types Using wget -r -A

You can use this under following situations:

Download all images from a website
Download all videos from a website
Download all PDF files from a website

$ wget -r -A.pdf http://url-to-webpage-with-pdfs/

	def argmax1(array):
	return array.index(max(array))

	def argmax2(array):
	return max(range(len(array)), key=lambda x: array[x])

	#-- coding: utf-8 --

	from collections import namedtuple


	class Immutable(namedtuple("Immutable", "x, y")):
	"""Immutable class using collections.namedtuple."""
	def __str__(self):
	return "class: {c}, x: {x}, y: {y}".format(c=Immutable.__name__,
	x=self.x, y=self.y)

	/* garp.c - Send IPv4 Gratuitous ARP Packet

	Usage Example: sudo ./garp eth0

	Copyright (C) 2011-2013 P.D. Buchan (pdbuchan@yahoo.com)
	Copyright (C) 2013 Seungwon Jeong (seungwon0@gmail.com)

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or

	function mycd()
	{
	#if this directory is writable then write to directory-based history file
	#otherwise write history in the usual home-based history file
	tmpDir=$PWD
	echo "#"`date '+%s'` >> $HISTFILE
	echo $USER' has exited '$PWD' for '$@ >> $HISTFILE
	builtin cd "$@" # do actual cd
	if [ -w $PWD ]; then export HISTFILE="$PWD/.dir_bash_history"; touch $HISTFILE; chmod --silent 777 $HISTFILE;
	else export HISTFILE="$HOME/.bash_history";

	#include <stdio.h>
	#include <string.h>
	#include <stdlib.h>
	#include <unistd.h>
	#include <fcntl.h>

	#include <netinet/tcp.h>
	#include <sys/socket.h>
	#include <sys/types.h>
	#include <netinet/in.h>

	wget --no-check-certificate --content-disposition https://github.com/joyent/node/tarball/v0.7.1
	# --no-check-cerftificate was necessary for me to have wget not puke about https
	curl -LJO https://github.com/joyent/node/tarball/v0.7.1