How to generate random numbers biased towards one value in a range?

Question

Say, if I wanted to generate an unbiased random number between min and max, I\'d do:

var rand = function(min, max) {
    return Mat         


        

Answer 1

Just for fun, here's a version that relies on the Gaussian function, as mentioned in SpiderPig's comment to your question. The Gaussian function is applied to a random number between 1 and 100, where the height of the bell indicates how close the final value will be to N. I interpreted the degree D to mean how likely the final value is to be close to N, and so D corresponds to the width of the bell - the smaller D is, the less likely is the bias. Clearly, the example could be further calibrated.

(I copied Ken Fyrstenberg's canvas method to demonstrate the function.)

function randBias(min, max, N, D) {
  var a = 1,
      b = 50,
      c = D;

  var influence = Math.floor(Math.random() * (101)),
    x = Math.floor(Math.random() * (max - min + 1)) + min;

  return x > N 
         ? x + Math.floor(gauss(influence) * (N - x)) 
         : x - Math.floor(gauss(influence) * (x - N));

  function gauss(x) {
    return a * Math.exp(-(x - b) * (x - b) / (2 * c * c));
  }
}

var ctx = document.querySelector("canvas").getContext("2d");
ctx.fillStyle = "red";
ctx.fillRect(399, 0, 2, 110);
ctx.fillStyle = "rgba(0,0,0,0.07)";

(function loop() {
  for (var i = 0; i < 5; i++) {
    ctx.fillRect(randBias(0, 600, 400, 50), 4, 2, 50);
    ctx.fillRect(randBias(0, 600, 400, 10), 55, 2, 50);
    ctx.fillRect(Math.random() * 600, 115, 2, 35);
  }
  requestAnimationFrame(loop);
})();