Javascript: Cant get a round number

Question

I tried nearly everything but cant seem to get the final result as a round number up to 2 decimal digits. It's a standard deviation

Thank you in advance, here is the code.

function round(number) {
  var final = Math.round(number * 100) / 100;
  return final;
}
function stdev(arr) {
  var avg = average(arr);
  var squareDiff = arr.map(function(arr) {
    var diff = arr - avg;
    var sqrDiff = diff * diff;
    return sqrDiff;
  });
  var avgSquareDiff = average(squareDiff);
  var stdDev = Math.sqrt(avgSquareDiff);
  return stdDev;
  function average(data) {
    var sum = data.reduce(function(sum, arr) {
      return sum + arr;
    }, 0);
    return round(sum / data.length);
  }
}

try .toFixed(2) ,this could be of some help to you https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toFixed — Geeky, Nov 06 '16 at 02:44
http://stackoverflow.com/questions/11832914/round-to-at-most-2-decimal-places-in-javascript This might work for you but I'm not entirely sure if this is what you need. — CristianHG, Nov 06 '16 at 02:44

score 2 · Accepted Answer · answered Nov 06 '16 at 02:44

You round the value when you return in average.

However, in stdev, then you calculate the square root of that rounded value.

That operation will most likely return a number with lots of decimals, and you return it directly without rounding it again.

Most probably you need

function round(number) {
  var final = Math.round(number * 100) / 100;
  return final;
}
function average(data) {
  var sum = data.reduce(function(sum, arr) {
    return sum + arr;
  }, 0);
  return sum / data.length;
}
function stdev(arr) {
  var avg = average(arr);
  var squareDiff = arr.map(function(arr) {
    var diff = arr - avg;
    var sqrDiff = diff * diff;
    return sqrDiff;
  });
  var avgSquareDiff = average(squareDiff);
  var stdDev = Math.sqrt(avgSquareDiff);
  return round(stdDev);
}

thanks that seems to work, just one more question, i am having some hoisting issues, i am getting this error: 'average' was used before it was defined — afkvision, Nov 06 '16 at 03:17
In your code you use `average` before defining it, but it's OK due to hoisting. In my code I don't use `average` before defining it. — Oriol, Nov 06 '16 at 03:21

Javascript: Cant get a round number

1 Answers1