ecmascript:

function initialize()
{
    Browser.println ('groundColorSunrise length=' + groundColorSunrise.length + ' '  + groundColorSunrise.toString());
    Browser.println ('groundColorNoon    length=' +    groundColorNoon.length +    ' '  + groundColorNoon.toString());
    Browser.println ('groundColorSunset  length=' +  groundColorSunset.length +  ' '  + groundColorSunset.toString());
    Browser.println ('groundColorNight   length=' +   groundColorNight.length +   ' '  + groundColorNight.toString());
    Browser.println ('skyColorSunrise    length=' +    skyColorSunrise.length +    ' '  + skyColorSunrise.toString());
    Browser.println ('skyColorNoon       length=' +       skyColorNoon.length +       ' '  + skyColorNoon.toString());
    Browser.println ('skyColorSunset     length=' +     skyColorSunset.length +     ' '  + skyColorSunset.toString());
    Browser.println ('skyColorNight      length=' +      skyColorNight.length +      ' '  + skyColorNight.toString());
}
function set_fraction (fraction) // fraction is input value sent by TimeSensor clock
{
    // Sunrise to Noon, fraction 0.0 to 0.25, interval=0.25
    if      (fraction < 0.25)
    {
        groundColor_changed = interpolate (groundColorSunrise, groundColorNoon, fraction, 0.00, 0.25);
           skyColor_changed = interpolate (   skyColorSunrise,    skyColorNoon, fraction, 0.00, 0.25);
    }
    // Noon to Evening, fraction 0.25 to 0.5, interval=0.25
    else if (fraction < 0.5)
    {
        groundColor_changed = interpolate (groundColorNoon, groundColorSunset, fraction, 0.25, 0.25);
           skyColor_changed = interpolate (   skyColorNoon,    skyColorSunset, fraction, 0.25, 0.25);
    }
    // Evening to Night, fraction 0.5 to 0.6, interval=0.1
    else if (fraction < 0.6)
    {
        groundColor_changed = interpolate (groundColorSunset, groundColorNight, fraction, 0.5, 0.1);
           skyColor_changed = interpolate (   skyColorSunset,    skyColorNight, fraction, 0.5, 0.1);
    }
    // Night (unchanging), fraction 0.6 to 0.95, interval=0.35
    else if (fraction < 0.95)
    {
        groundColor_changed = groundColorNight;
           skyColor_changed = skyColorNight;
    }
    // Night to Sunrise, fraction 0.95 to 1.0, interval=0.05
    else // (fraction < 1.0)
    {
        groundColor_changed = interpolate (groundColorNight, groundColorSunrise, fraction, 0.95, 0.05);
           skyColor_changed = interpolate (   skyColorNight,    skyColorSunrise, fraction, 0.95, 0.05);
    }
//    Browser.println ('groundColor_changed=' + groundColor_changed.toString());
//    Browser.println ('   skyColor_changed=' +    skyColor_changed.toString());
}
function interpolate (firstColorArray, secondColorArray, fraction, initialFraction, interval)
{
    f = (fraction - initialFraction) / interval; // f should range from 0 to 1
//  Browser.println ('initialFraction=' + initialFraction + ', fraction=' + fraction + ', f=' + f);

    color0 = firstColorArray[0] + (secondColorArray[0] - firstColorArray[0]) * f;
    color1 = firstColorArray[1] + (secondColorArray[1] - firstColorArray[1]) * f;
    color2 = firstColorArray[2] + (secondColorArray[2] - firstColorArray[2]) * f;
    color3 = firstColorArray[3] + (secondColorArray[3] - firstColorArray[3]) * f;
    color4 = firstColorArray[4] + (secondColorArray[4] - firstColorArray[4]) * f;
    return new MFColor (color0, color1, color2, color3, color4);
}