Hi Santhakumar:
I'm not sure if I understood what you mean. If you want to find the area under the plot, you can find this function under Signal Processing Reference. It is the Integrate method and has the following format:
public static double[] Integrate(
double[] inputData,
double dt,
double initialCondition,
double finalCondition);
If you have other questions, please let me know and I would be glad to help you.
Thank you
Nandini
NI