function switchCal (oldM,newM) {
    var oldMon = "calMon" + oldM;
    var newMon = "calMon" + newM;
    oldM = "cal"+oldM;
    newM = "cal"+newM;
    if (document.getElementById(oldM)) { document.getElementById(oldM).style.display = "none"; }
    if (document.getElementById(newM)) { document.getElementById(newM).style.display = "block"; }
    if (document.getElementById(oldMon)) { document.getElementById(oldMon).style.display = "none"; }
    if (document.getElementById(newMon)) { document.getElementById(newMon).style.display = "block"; }
   }