function show_app()
{
    swimming_pool_form.reset();
    potable_form.reset();
    seawater_form.reset();
    app4_form.reset();
    cooling_tower_form.reset();
    
    document.getElementById("swimming_pool_form").reset();
    document.getElementById("potable_form").reset();
    document.getElementById("seawater_form").reset();
    document.getElementById("app4_form").reset();
    document.getElementById("cooling_tower_form").reset();
    
    var swimming = document.getElementById("swimming_pool_table");
    var potable = document.getElementById("potable_table");
    var seawater = document.getElementById("seawater_table");
    var app4 = document.getElementById("app4");
    var cooling_tower = document.getElementById("cooling_tower");
    var app_index = document.getElementById("apps_list").options[document.getElementById("apps_list").selectedIndex].value;
    show_table();

    switch(app_index)
    {
        case "1":
        {
            swimming.style.visibility="visible";
            potable.style.visibility="hidden";
            seawater.style.visibility="hidden";
            app4.style.visibility="hidden";
            cooling_tower.style.visibility="hidden";
            swimming.style.position="static";
            potable.style.position="absolute";
            seawater.style.position="absolute";
            app4.style.position="absolute";
            cooling_tower.style.position="absolute";
            break;
        }
        case "2":
        {
            swimming.style.visibility="hidden";
            potable.style.visibility="visible";
            seawater.style.visibility="hidden";
            app4.style.visibility="hidden";
            cooling_tower.style.visibility="hidden";
            swimming.style.position="absolute";
            potable.style.position="static";
            seawater.style.position="absolute";
            app4.style.position="absolute";
            cooling_tower.style.position="absolute";
            break;
        }
        case "3":
        {
            swimming.style.visibility="hidden";
            potable.style.visibility="hidden";
            seawater.style.visibility="visible";
            app4.style.visibility="hidden";
            cooling_tower.style.visibility="hidden";
            swimming.style.position="absolute";
            potable.style.position="absolute";
            seawater.style.position="static";
            app4.style.position="absolute";
            cooling_tower.style.position="absolute";
            break;
        }
        case "4":
        {
            swimming.style.visibility="hidden";
            potable.style.visibility="hidden";
            seawater.style.visibility="hidden";
            app4.style.visibility="visible";
            cooling_tower.style.visibility="hidden";
            swimming.style.position="absolute";
            potable.style.position="absolute";
            seawater.style.position="absolute";
            app4.style.position="static";
            cooling_tower.style.position="absolute";
            break;
        }
        case "5":
        {
            swimming.style.visibility="hidden";
            potable.style.visibility="hidden";
            seawater.style.visibility="hidden";
            app4.style.visibility="hidden";
            cooling_tower.style.visibility="visible";
            swimming.style.position="absolute";
            potable.style.position="absolute";
            seawater.style.position="absolute";
            app4.style.position="absolute";
            cooling_tower.style.position="static";
            break;
        }
        default:
        {
            swimming.style.visibility="hidden";
            potable.style.visibility="hidden";
            seawater.style.visibility="hidden";
            app4.style.visibility="hidden";
            cooling_tower.style.visibility="hidden";
            swimming.style.position="absolute";
            potable.style.position="absolute";
            seawater.style.position="absolute";
            app4.style.position="absolute";
            cooling_tower.style.position="absolute";
            break;
        }
    }
}

function calculate_swimming()
{
    var volume = document.getElementById("pool_volume").value;    /* get pool volume */
    var factor = document.getElementById("pool_volume_unit").options[document.getElementById("pool_volume_unit").selectedIndex].value; /* get metric value */
    document.getElementById("swimming_output").value=volume*factor; /* volume x metric value */
    document.getElementById("swimming_output").value = document.getElementById("swimming_output").value.substring(document.getElementById("swimming_output").value.lastIndexOf);
    show_table(document.getElementById("salinity").options[document.getElementById("salinity").selectedIndex].value);
}

function calculate_potable()
{
    var volume = document.getElementById("avg_flow").value;
    var factor = document.getElementById("flow_volume_unit").options[document.getElementById("flow_volume_unit").selectedIndex].value;
    var dose = document.getElementById("cl_dose1").value;
    document.getElementById("potable_output").value=volume*factor*dose;
    document.getElementById("potable_output").value = document.getElementById("potable_output").value.substring(0,document.getElementById("potable_output").value.lastIndexOf(".")+3);
    show_table("b");
}

function calculate_seawater()
{
    var volume = document.getElementById("seawater_flow").value;
    var factor = document.getElementById("seawater_volume_unit").options[document.getElementById("seawater_volume_unit").selectedIndex].value;
    var dose = document.getElementById("cl_dose2").value;
    document.getElementById("seawater_output").value=volume*factor*dose;
    document.getElementById("seawater_output").value = document.getElementById("seawater_output").value.substring(0,document.getElementById("seawater_output").value.lastIndexOf(".")+3);
    show_table("c");
}

function show_table(theTable)
{
    var tableA = document.getElementById("tableA");
    var tableB = document.getElementById("tableB");
    var tableC = document.getElementById("tableC");
    var tableD = document.getElementById("tableD");
    var defaultTable = document.getElementById("defaultTable");

    switch(theTable)
    {
        case "a":
        {
            tableA.style.visibility="visible";
            tableB.style.visibility="hidden";
            tableC.style.visibility="hidden";
            tableD.style.visibility="hidden";
            defaultTable.style.visibility="hidden";
            tableA.style.position="static";
            tableB.style.position="absolute";
            tableC.style.position="absolute";
            tableD.style.position="absolute";
            defaultTable.style.position="absolute";
            break;
        }
        case "b":
        {
            tableA.style.visibility="hidden";
            tableB.style.visibility="visible";
            tableC.style.visibility="hidden";
            tableD.style.visibility="hidden";
            defaultTable.style.visibility="hidden";
            tableA.style.position="absolute";
            tableB.style.position="static";
            tableC.style.position="absolute";
            tableD.style.position="absolute";
            defaultTable.style.position="absolute";
            break;
        }
        case "c":
        {
            tableA.style.visibility="hidden";
            tableB.style.visibility="hidden";
            tableC.style.visibility="visible";
            tableD.style.visibility="hidden";
            defaultTable.style.visibility="hidden";
            tableA.style.position="absolute";
            tableB.style.position="absolute";
            tableC.style.position="static";
            tableD.style.position="absolute";
            defaultTable.style.position="absolute";
            break;
        }
        case "d":
        {
            tableA.style.visibility="hidden";
            tableB.style.visibility="hidden";
            tableC.style.visibility="hidden";
            tableD.style.visibility="visible";
            defaultTable.style.visibility="hidden";
            tableA.style.position="absolute";
            tableB.style.position="absolute";
            tableC.style.position="absolute";
            tableD.style.position="static";
            defaultTable.style.position="absolute";
            break;
        }
        default:
        {
            tableA.style.visibility="hidden";
            tableB.style.visibility="hidden";
            tableC.style.visibility="hidden";
            tableD.style.visibility="hidden";
            defaultTable.style.visibility="visible";
            tableA.style.position="absolute";
            tableB.style.position="absolute";
            tableC.style.position="absolute";
            tableD.style.position="absolute";
            defaultTable.style.position="static";
            break;
        }
    }
}