thanks for the help ,
sorry for the "*" sign , what i meant was "-"
i can fix on that equation its giving me better results..... when i sweep the resistance values, the efficiency at a particular vale of resistance was about 76% , but i am not able to judge if it is right. besides i tried another equation to calculate the input power.... but i dont know wheather it sounds reliable
integral((vplus(t)*(iplus(t)) +(vminus(t)* iminus(t)))
if you dont mind could please tell me if it is worth , because i dont get the same results as the equation which you have suggested
thanks