it does not work ,why?
a=[1 ,2 ,3 ,4]
b=[7 8 9 5]
foo=x->fft(x,2)
foo.(b)
#print(fft(b,2))
It’s not clear what you really want to do. foo.(b), written with the dot, is asking foo, and thus fft, to act element-wise on b, but fft requires an Array argument.