make_county_prediction

function make_county_prediction($county,$start,$count,$t,$dt){
    global $core;
    $return = '';
    $start = new DateTime ($start, new DateTimeZone ('UTC'));
    $end = new DateTime (' +30 days', new DateTimeZone ('UTC'));
    $interval = new DateInterval ('P1D');
    $range = new DatePeriod ($start, $interval, $end);
    $N = $count; // total cases
    $Nmax = total_count($county); // population
    $a = '0.394'; // percentage daily infection rate
    foreach ($range as $date) {
        $out = $date->format ('Y-m-j');
        //$N=$N+$a*(1-$N/$Nmax)*$N*$dt;
        //$t=$t+$dt;
        $Nold=$N;
        $N=$N+$a*(1-$N/$Nmax)*$N*$dt;
        $r=($N-$Nold)/$dt;
            $return .= '{ label: "'.$out.'", y: '.$r.' }, ';
    }
    return $return;
}