hermitian symmetry in IFFT !

Hi all. I have a matrix as a 2D spectrum. now, I want to transform it to time domain. when I use IFFT, the results are complex numbers, but it should be real numbers! so I have to have hermitain symmetry. how can i do that?

[Walter Roberson]

What is the relative scale of the complex portion? Could you simply be encountering round-off problems?

[rahman]

it is about the real part.

[Walter Roberson]

Can you create a small example?

Are you doing anything between the fft and ifft ?

Answer 1

[Honglei Chen]

If it is some small imaginary part due to numerical precisions, you can probably preprocess your input to IFFT by doing

x = (x+x')/2

This makes x Hermitian

Answer 2

[Jakob Ameres]

Use the symmetric flag for the ifft.

ifft( data, [], dim, 'symmetric')