Band pass filter in frequency domain

I have some big data in time doamin. I converted that data into frequncy domain by applying FFT. I want to apply bandpass filter to this data. I tried with different commands like 'bandpass, filter, butter, etc' but i am not getting expected results. I am thinking all the commands are applicable to time doamin signal. Can someone help me out in understanding how to apply bandpass to fft data.

Thanks in advance

Answer 1

[Star Strider]

Please do not even try to do filtering in the frequency domain. However, if you absolutely must, use the fftfilt function.

[Mordehay Moradi]

Why do you say not filtering in the f-domain? what is wrong with that?

[Star Strider]

@Mordehay Moradi — There’s nothing wrong with it if you’re doing it with analogue hardware filters, because they operate in the frequency domain. However everything in a computer uses sampled, discrete, signals, so it is in the time domain essentially by definition.

Even if you use the convolution of a filter passband and the spectrum of a signal created by calculating the Fourier transforms, you are doing that filtering by creating the frequency domain representation of a sampled signal first.

So stay in the time domain with sampled signals. It¹s just easier.