Parseval’s theorem — energy in time equals energy in frequency
Parseval’s theorem (Plancherel): sum/integral of |x|² equals sum/integral of |X|² (with consistent DFT scaling). Derivation intuition and FFT checks.
Parseval’s theorem
RMS (root mean square) value — meaning, formula, and signal power
What RMS means for voltages and DSP signals, how it ties to average power, and the formulas for continuous and discrete waveforms.