Dear all,

Consider M = 16 w = [ones(1,M/4),zeros(1,M/4)] w = [w(1:M/2), 0, conj(w($:-1:2))] v = ifft(w) isreal(v) The first 3 lines defines a real spectrum of a real signal, then the real signal is recovered and finally it is checked whether it is real or not. What puzzles me is that the result is T (true). However, the definition of the ifft() involves complex operations, so at some point the numbers must be converted to a complex representation such as 1. + 0.i so I would expect that the result included 0i so the result of the test should be F. Where is this null imaginary component removed? I don't say this is wrong, but it is perplexing if compared to much more simple operations such as sqrt(%i^4) which yields 1. + 0.i, a complex representation of real scalar 1. Maybe the fftw package is so refined to detect whether the result is actually real and removes the useless 0.i components? Regards, Federico Miyara -- El software de antivirus Avast ha analizado este correo electrÃ³nico en busca de virus. https://www.avast.com/antivirus

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