rounding numbers up in javascript having problems

Question

hey i am having problems with rounding up numbers because Im not sure how i would go about doing it this is the code is use for the maths:

    var lon1 = position.coords.longitude* 0.0174532925;
    var lat1 = position.coords.latitude * 0.0174532925;
    var i = 0;

    while (i<locations.length)
    {
        x.innerHTML+= "<br>Distance " + calcDist(lon1, lat1, locations[i][1]* 0.0174532925, locations[i][2]* 0.0174532925);
        i++;
    }       
    }   
    function calcDist(lon1, lat1, lon2, lat2)
    {
        return Math.acos(Math.sin(lat1)*Math.sin(lat2) + 
        Math.cos(lat1)*Math.cos(lat2) *
        Math.cos(lon2-lon1)) * 3958;    
    }

the reason i am asking is because i am creating a store locator and this is for the distance between the two points the user and the store but when it works it out it shows as 5.595255493978103 instead of 5.6 miles

any help would be much appreciated thanks in advance

Deestan · Accepted Answer · 2013-09-26T09:18:02.303

1

// Round towards nearest multiple of 0.1
function round(x) {
    return Math.round(x * 10) / 10;
}

x.innerHTML+= "<br>Distance " + round(calcDist(lon1, lat1, locations[i][1]* 0.0174532925, locations[i][2]* 0.0174532925));

edited Sep 26 '13 at 09:18

answered Sep 26 '13 at 09:07

Deestan

16,738
4
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I'd probably use `Math.ceil`, but otherwise good answer. – Daniël W. Crompton Sep 26 '13 at 09:12
@DaniëlW.Crompton I'm rounding towards the nearest number, though, as I assumed that was what he *really* wanted. With `Math.ceil`, remember to adjust the `+ 0.5` to `- 0.5`, or just remove it if you want to round strictly up. – Deestan Sep 26 '13 at 09:14
...or just use `Math.round`. Derp. Forgot about that one. – Deestan Sep 26 '13 at 09:17
this has worked perfectly thank you very much – Pazrat Sep 26 '13 at 09:35

score 0 · Answer 2 · answered Sep 26 '13 at 09:17

0

 // Round towards nearest multiple of 0.1
 function round(num){
     return Math.round(num*10)/10;
 }

So...
round(3.14) = 3.1;
round(3.15) = 3.2;

Or for custom number of dps

function round (num,dp){
  var scale = Math.pow(10,dp);
  return Math.round(num*scale)/scale;
}

So...
round(3.456,2) = 2.46;
round(3.456,1) = 2.5;
roudn(3.456,0) = 2;

answered Sep 26 '13 at 09:17

Chris Charles

4,406
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this has worked great thanks – Pazrat Sep 26 '13 at 09:36

Moax6629 · Answer 3 · 2013-09-26T09:24:18.523

-1

you can use Math.round() on values you intended to round!

edited Sep 26 '13 at 09:24

answered Sep 26 '13 at 09:13

Moax6629

378
4
14

rounding numbers up in javascript having problems

3 Answers3