x = INVERSEFOURIERTRANSFORM(Cx,dF) gives the real time series from the complex Fourier transform taken at the sampling frequency interval dF, via FFT.
The components must be taken only at positive Fourier frequencies, from zero to Nyquist. This is one of the purposes of this simple program and the FOURIERTRANSFORM.M (here at the FEx): only positive frequencies.

The other purpose is for the user to see how to get the same result via complex exponentials or Fourier trigonometric series (sines and cosines), although this methods are slower than FFT.

Another purpose is understand the diference between the components defined by the book of Percival & Walden and the one by Bloomfield.

The M-file comes with the example of the screenshot.

See also:
http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=13327