<html>
<head>
<script>
//
// pi.html
// Neil Gershenfeld 1/24/17
// pi calculation benchmark
// pi = 3.14159265358979323846
//
function serial_benchmark() {
var points = parseInt(document.getElementById('serial_points').value)
var a = 0.5
var b = 0.75
var c = 0.25
var pi = 0
var tstart = Date.now()/1000
for (var i = 1; i <= points; ++i)
pi += a/((i-b)*(i-c))
var tend = Date.now()/1000
var mflops = points*5.0*1e-6/(tend-tstart)
document.getElementById('div_pi_serial').innerHTML = 'pi: '+pi
document.getElementById('div_time_serial').innerHTML = 'time: '+(tend-tstart).toFixed(1)+'s'
document.getElementById('div_flop_serial').innerHTML = 'estimated MFlops: '+mflops.toFixed(1)
}
function reduce_benchmark() {
var points = parseInt(document.getElementById('reduce_points').value)
var a = 0.5
var b = 0.75
var c = 0.25
var tstart = Date.now()/1000
var array = new Float64Array(points)
var pi = array.reduce(function(sum,val,i,arr){return sum+a/(((i+1)-b)*((i+1)-c))},0)
var tend = Date.now()/1000
var mflops = points*5.0*1e-6/(tend-tstart)
document.getElementById('div_pi_reduce').innerHTML = 'pi: '+pi
document.getElementById('div_time_reduce').innerHTML = 'time: '+(tend-tstart).toFixed(1)+'s'
document.getElementById('div_flop_reduce').innerHTML = 'estimated MFlops: '+mflops.toFixed(1)
}
function parallel_benchmark() {
document.getElementById('div_flop_parallel').innerHTML = 'estimated MFlops: calculating ...'
var threads = parseInt(document.getElementById('parallel_threads').value)
var points = parseInt(document.getElementById('parallel_points').value)
var results = []
var workers = new Array(threads)
var blob = new Blob(['('+parallel_worker.toString()+'())'])
var url = window.URL.createObjectURL(blob)
var tstart = Date.now()/1000
for (var t = 0; t < threads; ++t) {
workers[t] = new Worker(url)
workers[t].addEventListener('message',function(evt) {
results.push(evt.data.sum)
workers[evt.data.index].terminate()
if (results.length == threads) {
var tend = Date.now()/1000
var mflops = (threads*points)*5.0*1e-6/(tend-tstart)
var pi = results.reduce(function(x,y){return x+y},0)
document.getElementById('div_pi_parallel').innerHTML = 'pi: '+pi
document.getElementById('div_time_parallel').innerHTML = 'time: '+(tend-tstart).toFixed(1)+'s'
document.getElementById('div_flop_parallel').innerHTML = 'estimated MFlops: '+mflops.toFixed(1)
}
})
workers[t].postMessage({points:points,index:t})
}
window.URL.revokeObjectURL(url)
}
function parallel_worker() {
self.addEventListener('message',function(evt) {
var points = evt.data.points
var index = evt.data.index
var a = 0.5
var b = 0.75
var c = 0.25
var sum = 0
var istart = 1+points*index
var iend = points*(index+1)
for (var i = istart; i <= iend; ++i)
sum += a/((i-b)*(i-c))
self.postMessage({sum:sum,index:index})
})
}
</script>
</head>
<body>
<button onclick='serial_benchmark()'>calculate pi serial</button><br>
number of points: <input type='text' id='serial_points' value='1000000000' size=10>
<div id='div_pi_serial'>pi:</div>
<div id='div_time_serial'>time:</div>
<div id='div_flop_serial'>estimated MFlops:</div>
<br>
<button onclick='reduce_benchmark()'>calculate pi reduce</button><br>
number of points: <input type='text' id='reduce_points' value='10000000' size=10>
<div id='div_pi_reduce'>pi:</div>
<div id='div_time_reduce'>time:</div>
<div id='div_flop_reduce'>estimated MFlops:</div>
<br>
<button onclick='parallel_benchmark()'>calculate pi parallel</button><br>
number of workers: <input type='text' id='parallel_threads' value='4' size=3><br>
points per thread: <input type='text' id='parallel_points' value='1000000000' size=10>
<div id='div_pi_parallel'>pi:</div>
<div id='div_time_parallel'>time:</div>
<div id='div_flop_parallel'>estimated MFlops:</div>