Don Cross cosinekitty

## EarthRadius.js
function EarthRadiusInMeters(latitudeRadians)
{
    // latitudeRadians is geodetic, i.e. that reported by GPS.
    // http://en.wikipedia.org/wiki/Earth_radius
    var a = 6378137.0;  // equatorial radius in meters
    var b = 6356752.3;  // polar radius in meters
    var cos = Math.cos(latitudeRadians);
    var sin = Math.sin(latitudeRadians);
    var t1 = a * a * cos;
    var t2 = b * b * sin;

## LocationToPoint.js
function LocationToPoint(c)
{
    // Convert (lat, lon, elv) to (x, y, z).
    var lat = c.lat * Math.PI / 180.0;
    var lon = c.lon * Math.PI / 180.0;
    var radius = EarthRadiusInMeters(lat);
    var clat   = GeocentricLatitude(lat);

    var cosLon = Math.cos(lon);
    var sinLon = Math.sin(lon);

## RotateGlobe.js
function RotateGlobe(b, a, bradius, aradius)
{
    // Get modified coordinates of 'b' by rotating the globe so that 'a' is at lat=0, lon=0.
    var br = {lat:b.lat, lon:(b.lon - a.lon), elv:b.elv};
    var brp = LocationToPoint(br);

    // Rotate brp cartesian coordinates around the z-axis by a.lon degrees,
    // then around the y-axis by a.lat degrees.
    // Though we are decreasing by a.lat degrees, as seen above the y-axis,
    // this is a positive (counterclockwise) rotation (if B's longitude is east of A's).

## naive.py
#!/usr/bin/env python3
#
#   naive.py  -  by Don Cross
#
#   Illustrates why 4*arctan(1) is not a good way to calculate pi.
#   Calculates the series 4*(1/1 - 1/3 + 1/5 - 1/7 + ...)

import math

n = 1

## better.py
#!/usr/bin/env python3
#
#   better.py  -  by Don Cross
#
#   Test the formula pi = 4*(arctan(1/2) + arctan(1/3)).
#

import math

def ArctanDenom(d):

## machin.py
#!/usr/bin/env python3
#
#   machin.py  -  by Don Cross
#
#   Test Machin's Formula: pi = 4*(4*arctan(1/5) - arctan(1/239)).
#

import math

def ArctanDenom(d):

## picrunch.py
#!/usr/bin/env python3
#
#   picrunch.py  -  by Don Cross
#
#   Use Machin's Formula
#   pi = 4*(4*arctan(1/5) - arctan(1/239))
#   to calculate pi to one million places after the decimal.
#
import sys

## harmonograph.html
<!DOCTYPE html>
<html>
    <head>
        <title>Harmonograph simulation by Don Cross</title>
        <meta charset="UTF-8" />
        <link rel="stylesheet" href="harmonograph.css">
    </head>
    <body>
        <div><canvas id="GraphCanvas" class="HarmonographCanvas"></canvas></div>
        <div>

## harmonograph.js
'use strict';

window.onload = function() {
    function Radians(d) {
        return d * (Math.PI / 180.0);
    }

    class Pendulum {
        constructor(xamplitude, yamplitude, frequency, phase, halflife) {
            this.xamplitude = xamplitude;

## harmonograph.css
html, body {
    /* Fit rendered page to screen layout */
    top:0;
    bottom:0;
    left:0;
    right:0;
    position:fixed;
}

.HarmonographCanvas {
	function EarthRadiusInMeters(latitudeRadians)
	{
	// latitudeRadians is geodetic, i.e. that reported by GPS.
	// http://en.wikipedia.org/wiki/Earth_radius
	var a = 6378137.0; // equatorial radius in meters
	var b = 6356752.3; // polar radius in meters
	var cos = Math.cos(latitudeRadians);
	var sin = Math.sin(latitudeRadians);
	var t1 = a * a * cos;
	var t2 = b * b * sin;
	function LocationToPoint(c)
	{
	// Convert (lat, lon, elv) to (x, y, z).
	var lat = c.lat * Math.PI / 180.0;
	var lon = c.lon * Math.PI / 180.0;
	var radius = EarthRadiusInMeters(lat);
	var clat = GeocentricLatitude(lat);

	var cosLon = Math.cos(lon);
	var sinLon = Math.sin(lon);
	function RotateGlobe(b, a, bradius, aradius)
	{
	// Get modified coordinates of 'b' by rotating the globe so that 'a' is at lat=0, lon=0.
	var br = {lat:b.lat, lon:(b.lon - a.lon), elv:b.elv};
	var brp = LocationToPoint(br);

	// Rotate brp cartesian coordinates around the z-axis by a.lon degrees,
	// then around the y-axis by a.lat degrees.
	// Though we are decreasing by a.lat degrees, as seen above the y-axis,
	// this is a positive (counterclockwise) rotation (if B's longitude is east of A's).
	#!/usr/bin/env python3
	#
	# naive.py - by Don Cross
	#
	# Illustrates why 4*arctan(1) is not a good way to calculate pi.
	# Calculates the series 4*(1/1 - 1/3 + 1/5 - 1/7 + ...)

	import math

	n = 1
	#!/usr/bin/env python3
	#
	# better.py - by Don Cross
	#
	# Test the formula pi = 4*(arctan(1/2) + arctan(1/3)).
	#

	import math

	def ArctanDenom(d):
	#!/usr/bin/env python3
	#
	# machin.py - by Don Cross
	#
	# Test Machin's Formula: pi = 4(4arctan(1/5) - arctan(1/239)).
	#

	import math

	def ArctanDenom(d):
	#!/usr/bin/env python3
	#
	# picrunch.py - by Don Cross
	#
	# Use Machin's Formula
	# pi = 4(4arctan(1/5) - arctan(1/239))
	# to calculate pi to one million places after the decimal.
	#
	import sys
	<!DOCTYPE html>
	<html>
	<head>
	<title>Harmonograph simulation by Don Cross</title>
	<meta charset="UTF-8" />
	<link rel="stylesheet" href="harmonograph.css">
	</head>
	<body>
	<div><canvas id="GraphCanvas" class="HarmonographCanvas"></canvas></div>
	<div>
	'use strict';

	window.onload = function() {
	function Radians(d) {
	return d * (Math.PI / 180.0);
	}

	class Pendulum {
	constructor(xamplitude, yamplitude, frequency, phase, halflife) {
	this.xamplitude = xamplitude;
	html, body {
	/* Fit rendered page to screen layout */
	top:0;
	bottom:0;
	left:0;
	right:0;
	position:fixed;
	}

	.HarmonographCanvas {