js file for my blog at http://randomthoughtsonjavaprogramming.blogspot.nl/p/measurements.html

compute_diet.js

function computeDiet(now)
{
    var beginning = new Date("March 1, 2014 11:13:00");
    // from milliseconds to days = / 1000 / 60 / 60 / 24
    // from milliseconds to days = / 3600000 / 24
    var period = now.getTime()-beginning.getTime();
    var days = period / 3600000 / 24;
    var total_days = 365 * 2;
    var begin_weight = 98.6;
    var end_weight = 80.0;
    var result = begin_weight -       
      (begin_weight-end_weight)*(days/total_days);
    if (result < end_weight) {return end_weight;}
    return result; 
}

function computeMeasurements()
{
    var weights = measurements();
    var average_weight = 0;
    var average_impedance = 0;
    var steps = 10; // window for the moving average

    for (var x in weights)
    {   
        weights[x].measurementTimestamp = new Date(weights[x].measurementTimestamp);
        weights[x].registrationTimestamp = new Date(weights[x].registrationTimestamp);
        weights[x].bmi = weights[x].weight / (1.96*1.96);
        weights[x].dietWeight = computeDiet(weights[x].registrationTimestamp);
    }
    weights.sort(function(a,b){return a.registrationTimestamp.getTime()-b.registrationTimestamp.getTime()});
    if (average_weight === 0)
    {
        average_weight = weights[0].weight;            
    }
    if (average_impedance === 0)
    {
        average_impedance = weights[0].impedance;
    }        
    for (var x in weights)
    {   
        average_weight = (steps * average_weight + weights[x].weight - (x-steps < 0 ? average_weight : weights[x-steps].averageWeight)) / steps
        weights[x].averageWeight = average_weight;
        average_impedance = (steps * average_impedance + weights[x].impedance - (x-steps < 0 ? average_impedance : weights[x-steps].averageImpedance)) / steps
        weights[x].averageImpedance = average_impedance;
    }
    return weights;
}