LTSPICE is a wonderful CAD tool developed by Linear technology ( now Analog Devices Inc) that can be accessed from Analog for simulation. It is a very professional CAD tool with many controls. One of these is the calculation of rms values of a waveform ( cntrl>left click). However, we found that the user needs to beware. LTSPICE can give you erroneous results, not because it is not working correhttp://www.signalpro.bizctly but because of the way it calculates rms values. Make sure that you do the hand calculations before using this feature. Please visit the SPG website with more info on other topics of interest.