Discrete Fourier transform of Time series

I have data of electricity consumption by date, I need a matlab code;

1. to convert the data to frequencies
2. to use low pass filter to get the low frequencies based on a frequency cut off.

Thanks

Answer 1

[Star Strider]

See the documentation on fft (link), and the documentation on lowpass (link). (The lowpass function was introduced in R2018a.)