function clearFields() {
        document.getElementById('converter').one.value = "";
        document.getElementById('converter').two.value = "";
}

function sendError() {
        alert("Please enter a number.");
}

function checknumber() {
        var x = document.getElementById('converter').one.value;
        var y = document.getElementById('converter').two.value;
var nx = x.split("");
var ny = y.split("");
if(nx[0] == "-") { x = nx[1];}
if(ny[0] == "-") { y = ny[1];}
        var anum = /(^\d+$)|(^\d+\.\d+$)/;
        if ( (anum.test(x) || anum.test(y)) && (x != "" || y != "") )
                testresult=true;
        else {
                alert("Please enter a valid number.");
                testresult=false;
        }
        return (testresult);
}
function updateCelsius() {
document.getElementById('converter').two.value = Math.round((5.0/9.0) * (document.getElementById('converter').one.value - 32.0));
}
function updateFahrenheit() {
document.getElementById('converter').one.value = Math.round((9.0/5.0) * document.getElementById('converter').two.value + 32.0);
}
function convertTemperature() 
{
if ( (document.getElementById('converter').one.value != "") && (document.getElementById('converter').two.value == "") )
{
if(checknumber())
{
updateCelsius();
}
}
else if( (document.getElementById('converter').one.value == "") && (document.getElementById('converter').two.value != "") )
{
if(checknumber())
{
updateFahrenheit();
}
}
else if( (document.getElementById('converter').one.value == "") && (document.getElementById('converter').two.value == "") )
{
sendError();
}
else
{
if(checknumber())
{
document.getElementById('converter').two.value = "";
updateCelsius();
}
}
}