I can\'t get my head around this, which is more random?
rand()
OR:
rand() * rand()
I´m f
Assuming that rand()
returns a number between [0, 1)
it is obvious that rand() * rand()
will be biased toward 0. This is because multiplying x
by a number between [0, 1)
will result in a number smaller than x
. Here is the distribution of 10000 more random numbers:
google.charts.load("current", { packages: ["corechart"] });
google.charts.setOnLoadCallback(drawChart);
function drawChart() {
var i;
var randomNumbers = [];
for (i = 0; i < 10000; i++) {
randomNumbers.push(Math.random() * Math.random());
}
var chart = new google.visualization.Histogram(document.getElementById("chart-1"));
var data = new google.visualization.DataTable();
data.addColumn("number", "Value");
randomNumbers.forEach(function(randomNumber) {
data.addRow([randomNumber]);
});
chart.draw(data, {
title: randomNumbers.length + " rand() * rand() values between [0, 1)",
legend: { position: "none" }
});
}
Generating chart...
If rand()
returns an integer between [x, y]
then you have the following distribution. Notice the number of odd vs even values:
google.charts.load("current", { packages: ["corechart"] });
google.charts.setOnLoadCallback(drawChart);
document.querySelector("#draw-chart").addEventListener("click", drawChart);
function randomInt(min, max) {
return Math.floor(Math.random() * (max - min + 1)) + min;
}
function drawChart() {
var min = Number(document.querySelector("#rand-min").value);
var max = Number(document.querySelector("#rand-max").value);
if (min >= max) {
return;
}
var i;
var randomNumbers = [];
for (i = 0; i < 10000; i++) {
randomNumbers.push(randomInt(min, max) * randomInt(min, max));
}
var chart = new google.visualization.Histogram(document.getElementById("chart-1"));
var data = new google.visualization.DataTable();
data.addColumn("number", "Value");
randomNumbers.forEach(function(randomNumber) {
data.addRow([randomNumber]);
});
chart.draw(data, {
title: randomNumbers.length + " rand() * rand() values between [" + min + ", " + max + "]",
legend: { position: "none" },
histogram: { bucketSize: 1 }
});
}
Generating chart...