function calculate()
{
    var source_amount = document.calculator.source_amount.value;
    var x = document.calculator.sourcecurrency.options.selectedIndex;
    var source_currency = document.calculator.sourcecurrency.options[x].value;
    var y = document.calculator.targetcurrency.options.selectedIndex;
    var target_currency = document.calculator.targetcurrency.options[y].value;
    var result = source_amount * source_currency / target_currency;
    result = Math.round(result * 100)/100;
    document.calculator.result.value = result;
    var mysc = document.calculator.sourcecurrency.options[x].text.split(" - ");
    var mytc = document.calculator.targetcurrency.options[y].text.split(" - ");
    //   document.cookie = "sourcecurrency=" + document.calculator.sourcecurrency.options[x].text + "; expires=Tue, 01-Jan-05 00:00:01 GMT";
    //   document.cookie = "targetcurrency=" + document.calculator.targetcurrency.options[y].text + "; expires=Tue, 01-Jan-05 00:00:01 GMT";

//alert('setting source cookie: '+mysc[1]);
//alert('setting target cookie: '+mytc[1]);
    document.cookie = "sourcecurrency=" + mysc[1] + ";";
    document.cookie = "targetcurrency=" + mytc[1] + ";";
}