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@jboner
jboner / latency.txt
Last active May 8, 2025 06:10
Latency Numbers Every Programmer Should Know
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
@ttscoff
ttscoff / flavor.rb
Created September 16, 2012 16:01
Quick wrapper to convert Markdown to HTML via Github API
#!/usr/bin/ruby
# Convert a Markdown README to HTML with Github Flavored Markdown
# Github and Pygments styles are included in the output
#
# Requirements: json gem (`gem install json`)
#
# Input: STDIN or filename
# Output: STDOUT
# Arguments: "-c" to copy to clipboard (or "| pbcopy"), or "> filename.html" to output to a file
# cat README.md | flavor > README.html
@afgomez
afgomez / dmginstall.sh
Created November 29, 2012 22:29
Download and install a .dmg
#!/bin/bash
# Downloads and install a .dmg from a URL
#
# Usage
# $ dmginstall [url]
#
# For example, for installing alfred.app
# $ dmginstall http://cachefly.alfredapp.com/alfred_1.3.1_261.dmg
#
@going-digital
going-digital / fast_trig.frag
Created December 17, 2012 17:21
OpenGL ES Fast sin/cos functions. Double the speed of native on Raspberry Pi / Videocore IV
// Language is OpenGL ES, but gist.github.com doesn't know that language
//
// Approximation is based on multiply/accumulate, because thats the only
// thing Videocore can do quickly!
precision highp float;
float sinf(float x)
{
x*=0.159155;
@emeeks
emeeks / README.md
Last active March 25, 2024 07:56 — forked from mbostock/.block
An online tool for interactive teaching of network visualization and representation principles.

The range sliders at the top change the values for the force-directed algorithm and the buttons load new graphs and apply various techniques. This will hopefully serve as a tool for teaching network analysis and visualization principles during my Gephi courses and general Networks in the Humanities presentations.

Notice this includes a pretty straightforward way to load CSV node and edge lists as exported from Gephi.

It also includes a pathfinding algorithm built for the standard data structure of force-directed networks in D3. This requires the addition of .id attributes for the nodes, however.

Now with Clustering Coefficients!

Also, it loads images for nodes but the images are not in the gist. The code also refers to different network types but the data files on Gist only refer to the transportation network.

@caged
caged / svg-to-png.js
Created January 27, 2013 18:11
Convert SVG's to PNGs. This works OK if the SVG's styles are inline. The SVG element must contain an xmlns attribute. Webkit also requires you specify a font size on `text` elements.
var svg = document.getElementById('graph'),
xml = new XMLSerializer().serializeToString(svg),
data = "data:image/svg+xml;base64," + btoa(xml),
img = new Image()
img.setAttribute('src', data)
document.body.appendChild(img)
@xianyi
xianyi / test_dgetrf.c
Created February 12, 2013 16:31
Test dgetrf. gcc -o test test_dgetrf.c -I OpenBLAS_install/include OpenBLAS_install/lib/libopenblas.a -lpthread -lgfortran
#include <stdio.h>
#include "cblas.h"
#include "lapacke.h"
int main(int argc, char* argv[])
{
int* ipiv;
int info;
int i, j;
int n;
@Protonk
Protonk / prng.js
Last active August 31, 2024 17:14
Various PRNGs, implemented in javascript.
// Linear Congruential Generator
// Variant of a Lehman Generator
var lcg = (function() {
// Set to values from http://en.wikipedia.org/wiki/Numerical_Recipes
// m is basically chosen to be large (as it is the max period)
// and for its relationships to a and c
var m = 4294967296,
// a - 1 should be divisible by m's prime factors
a = 1664525,
// c and m should be co-prime
import numpy as np
import scipy.linalg.blas
cdef extern from "f2pyptr.h":
void *f2py_pointer(object) except NULL
ctypedef int dgemm_t(
char *transa, char *transb,
int *m, int *n, int *k,
double *alpha,
BIN = ./node_modules/.bin
SRC = $(wildcard src/*.coffee)
LIB = $(SRC:src/%.coffee=lib/%.js)
build: $(LIB)
lib/%.js: src/%.coffee
@mkdir -p $(@D)
@$(BIN)/coffee -bcp $< > $@