Hi Vinod
That was very useful, thank you! Your Notepad suggestion worked for some fields but not for the Dew Point field. This made a dim light bulb go off in my brain! I think the reason why I am getting "infinity" maths results is because temperature and dew point have different time stamps in the sql db. Naturally, Dew point has a different time stamp to the rest of the fields since it is a calculated param. By querying both variables for the latest entry in the same command, it only returns the value for one, not the other, hence the null value and the NaN/infinity maths result. What I need to do is query the variables separately and then do the maths ratio. Unfortunately when I tried it in Matlab, it didn't work either, but the gauge takes soooo long to load it is hard to work out what works and what doesn't. At least with your HTML script the result is instant. Thanks for pointing the way forward. I have something to go on with!
R