# parseval for a continuos but limited signal

I have a question about the parseval relation written here https://en.wikipedia.org/wiki/Parseval%27s_theorem (In the chapter Notation used in physics).

If I have a signal continuous but limited (so it does not go from $$\infty$$ to $$\infty$$ but from 0 to T, can The Parseval theorem be applied?

Sure. You can can just integrate in the time domain from $$0$$ to $$T$$ since the area outside $$[0, T]$$ is 0.
Please note that you still must integrate from $$-\infty$$ to $$+\infty$$ in the frequency domain since finite support in the time domain implies infinite support in the frequency domain (and vice versa).