juliusgeo

20 million digits of pi in under a minute with Julia

I recently discovered a relatively obscure algorithm for calculating the digits of pi: https://en.wikipedia.org/wiki/Gauss–Legendre_algorithm. Well, at least obscure compared to Chudnovsky's. Wikipedia notes that it is "memory-intensive" but is it really? Let's compare to the MPFR pi function:

function gauss_legendre(prec)
    setprecision(BigFloat, prec, base=10)
    GC.enable(false)

hirrolot

type term =
  | Lam of (term -> term)
  | Pi of term * (term -> term)
  | Appl of term * term
  | Ann of term * term
  | FreeVar of int
  | Star
  | Box

let unfurl lvl f = f (FreeVar lvl)

nicebyte

#pragma once

#define DYN_ARR_OF(type) struct  { \
  type *data; \
  type *endptr; \
  uint32_t capacity; \
}

#if !defined(__cplusplus)
#define decltype(x) void*

jzstark

Neural Style Transfer

Neural Style Transfer is the process of using Deep Neural Networks to migrate the semantic content of one image to different styles.

Usage

This gist implements NST in Owl, and provides a simple interfaces to use. Here is an example:

#zoo "6f28d54e69d1a19c1819f52c5b16c1a1"

garybernhardt

This document has moved!

It's now here, in The Programmer's Compendium. The content is the same as before, but being part of the compendium means that it's actively maintained.

akabe

(* ========================================================================== *
 * General implementation of A-star algorithm
 * ========================================================================== *)

module Astar :
sig
  type 'a t =
    {
      cost : 'a -> 'a -> int;
      goal : 'a;

PhDP

abstract Expr

type Const <: Expr; value::Int end
type Var <: Expr; name::String end
type Add <: Expr; left::Expr; right::Expr end
type Mult <: Expr; left::Expr; right::Expr end

add(x::Const, y::Const) = Const(x.value + y.value)
add(x::Const, y::Expr) = x.value == 0? y : Add(x, y)
add(x::Expr, y::Const) = add(y, x)

rmcgibbo

Open Computing Language (OpenCL) is a language and framework for writing computationally intensive kernels that run accross heterogenious platforms, including GPUs, CPUs, and perhaps other more esoteric devices.

Intel provides an OpenCL implementation for Intel CPUs, but there's not a lot of instructions on how to get it set up. Here's what I did.

Installing Intel CPU OpenCL on Ubuntu (12.04)

1. Download the Intel® SDK for OpenCL* Applications XE 2013 from the Intel website, here http://software.intel.com/en-us/vcsource/tools/opencl-sdk-xe. The download is a tarball -- the one I got is called intel_sdk_for_ocl_applications_2013_xe_sdk_3.0.67279_x64.tgz
2. Unpack the tarball and cd into the new directory

jackrusher

Hofstadter on Lisp

In the mid-80s, while reading through my roommate's collection of Scientific American back issues, I encountered this introduction to Lisp written by Douglas Hofstadter. I found it very charming at the time, and provide it here (somewhat illegally) for the edification of a new generation of Lispers.

In a testament to the timelessness of Lisp, you can still run all the examples below in emacs if you install these aliases:

(defalias 'plus #'+)
(defalias 'quotient #'/)
(defalias 'times #'*)
(defalias 'difference #'-)

NicolasT

type 'a writer = Buffer.t -> 'a -> unit;;
type 'a reader = string -> int -> ('a * int);;

let ($) a b = a b;;
let id x = x;;

let lift_llio_writer (l: Buffer.t -> 'b -> unit): ('a -> 'b) -> 'a writer =
    fun f -> fun b a ->
        let v = f a in
        l b v;;