Attempting to output value of math formula applied to array is failing [Jquery]

I'm attempting to get a coefficient of variation calculator working with jQuery, and can't seem to get it to output a correct answer.

My current code:

var fields = $('#cvform').serializeArray();
        var num = 0;
        var mean = 0;
        var m2 = 0;
        var total = 0;
        jQuery.each(fields, function(i, field){
        if (field.value > 0) {
            num++;
            var delta=(field.value-mean);
            var mean=(mean+delta/num);
            var m2=(m开发者_如何学运维2+delta*(field.value-mean));
            var total=(total+field.value);
        };
        });
        var cov=(((Math.sqrt(m2/(num-1)))/(total/num))*100);
        $("<span>Coefficient of Variation: " + delta + m2 + num + total + cov +  "</span>").appendTo('#cvdisplay');

When I attempt to output the values after, it tells me that delta is undefined, mean m2 and total are = 0, and num is output correctly. Cov is simply output as NaN. The array of #cvform is simply text inputs that can only be numbers. Can anyone point me in the right direction of getting this to function?

You declare delta within a function, so it isn't visible outside the for loop. Move its declaration out of the each block and it will be found.

var fields = $('#cvform').serializeArray();
    var num = 0,
        mean = 0,
        m2 = 0,
        total = 0,
        delta = 0;
    jQuery.each(fields, function(i, field){
    if (field.value > 0) {
        num++;
        delta=(field.value-mean);
        mean=(mean+delta/num);
        m2=(m2+delta*(field.value-mean));
        total=(total+field.value);
    };
    });
    var cov=(((Math.sqrt(m2/(num-1)))/(total/num))*100);
    $("<span>Coefficient of Variation: " + (delta + m2 + num + total + cov) +  "</span>").appendTo('#cvdisplay');