The phase of the fft is inverted

Hello!

I am obtaining the frf function of a signal by using th espectral densities in MATLAB. The magnitude of my frf seems fine, however, the phase is inverted in the sense that it should be ranging from 0 to -pi. Any help of what could be going on?

This is what I am getting:

And this is what I was expecting:

Thank you very much!!

[Bjorn Gustavsson]

Have you checked the sign and amplitude-conventions used by matlab and your reference source. This smells like that type of "error" - you think you've calculated the phase difference between signals y1 and y2 when what matlab gives you the phase-difference between y2 and y1.

[David Goodmanson]

Hi Carlota,

how, in terms of functions, are you calculating the frf?

You state that phase should be varying from 0 to -pi, but in the expected answer the phase is varying from pi to -pi. Could you comment?