RMS calculation in a spectral band

Hi guys, i'm in the early hours with matlab. Very trivial question : how do I calculate the RMS of a signal in a spectral band defined in a range of the resonant frequency, and then for the remaining band?

Thanks

[Mathieu NOE]

hello

see this :

relation between fft and rms - MATLAB Answers - MATLAB Central (mathworks.com)

you simply have to define the frequency range of interest and keep only the fft output that is in band