how can i get data sampling rate and FFT bin width?

hi, i have N=64 4d- fmri images with size matrix(128,128,64,90) where 90 is the number of time point and a 4d-image captured in T=2s. i want use fft matlab function. how can i calculate sample rate and fft width bin? What is the default value of the parameters fft?

Answer 1

[dpb]

"What is the default value of the parameters fft?"

None...the fft doesn't care, the sample rate is set solely by the data collection process.

If your images were captured at a uniform rate over a time perioed of 2 sec, then the sample rate would be 90/2 --> 45 Hz.

There's an example of using FFT fo compute a one-sided PSD in the doc for FFT that illustrates the time and frequency calculations.