CTMacUser’s gists

CTMacUser / Lucky Numbers.swift

Last active April 3, 2022 20:18

Using Swift to demonstrate the Sieve of Eratosthenes

	import Foundation


	/**
	Run an incremental counter, but return only the values that survive the "lucky number" process.

	The process is to list all the positive integers, then filter out entries in stages. For all the numbers in a stage, let N be the first unfiltered number that is neither 1 nor been already been used as a filter seed for a previous stage, and filter out every Nth number. The first pass uses 2 and therefore filters out every second number, i.e. the even numbers. The second pass uses 3 and therefore filters out every third number that survived the 2-stage. The third pass uses 7 and therefore filters out every seventh number that survived both the 2- and 3-stages. The fourth pass uses 9 and therefore filters out every ninth number that survived the 2-, 3-, and 7-stages. (Note that 2 is the only seed that eliminates itself in its filter. Some definitions of lucky numbers avoid this irregularity by starting with the odd positive integers.)
	*/
	public struct LuckyNumberGenerator<C

CTMacUser / remove_some_extents.cpp

Created April 25, 2013 22:07

Use when a built-in array types needs extents to be stripped, but the amount to strip is between one and all (exclusive). I thought I needed this for another project, but I ended up not needing it (yet). So it's here so I won't forget, and for posterity.

	// Copyright 2013 Daryle Walker.
	// Distributed under the Boost Software License, Version 1.0. (See a copy at
	// <http://www.boost.org/LICENSE_1_0.txt>.)

	#ifndef REMOVE_SOME_EXTENTS_HPP
	#define REMOVE_SOME_EXTENTS_HPP

	#include <cstddef>

CTMacUser / slice.cpp

Created April 3, 2013 00:07

An example program to create a variadic function that computes a chain of indexing expressions. It's a solution of a problem I posted at http://stackoverflow.com/q/10171525/1010226

	/*
	Demostration of variadic function template that runs a series of indexing
	expressions. Based of a problem I posted at
	http://stackoverflow.com/q/10171525/1010226

	Copyright (C) 2013 Daryle Walker
	I'm letting anyone use this code under the Boost Software License.
	*/
	#include <cassert>
	#include <cstddef>

CTMacUser / times.cpp

Created April 2, 2013 04:04

A custom literal suffix that returns an object that takes a function (object) for generic looping. C++11 required. The fact that the idea is theoretically and actually possible is amazing. I don't know if that's good or bad, yet.

	/*
	Copyright (C) 2013 by Daryle Walker

	Based on posts off the Boost mailing lists on 2013-Jan-31 by Tim
	Blechmann and TONGARI. C++11 is required; according to Live Work
	Space's code-runner (on 2013-Apr-1), only Clang >= 3.2 and
	GCC >= 4.7 accept it.

	The original post (Tim Blechmann) of the 7 in the thread:
	http://article.gmane.org/gmane.comp.lib.boost.devel/238310

CTMacUser / zipWith_demo.cpp

Created March 18, 2012 21:32

Improved version of my sample code from <http://stackoverflow.com/a/9736489/1010226>.

	// Taken from the final code I provided as an answer to a StackOverflow query
	// at <http://stackoverflow.com/a/9736489/1010226>.
	// Copyright 2012 by Daryle Walker

	#include <algorithm> // min
	#include <cassert> // assert
	#include <cmath> // pow
	#include <cstddef> // size_t
	#include <iostream> // cout
	#include <iterator> // back_inserter, begin, end

Daryle Walker CTMacUser