ReadUI
======
```{function}  ReadUI(files, path, freq, varargin)
```
Full definition:
```{code-block} matlab
function UI = ReadUI(files, path, freq, varargin)
```

read current and voltages from multiple files found in path

returns voltages/currents in time and frequency-domain

remarks on the frequency-domain:
- all signals are assumed to start at t=0
- currents that e.g. start at t = +delta_t/2 will be phase shifted by
   exp(-j*w*t(1))

optional parameter:
- freq: frequency-domain values will be calculated according to 'freq'
        if 'freq' is not given, a (zero padded) FFT will be used

optional key,value pairs:
- 'AR'  : auto-regressive model to improve FD accuracy
          values: order to use within an AR model or 'auto'

examples:

    U = ReadUI({'ut1_1','ut1_2'},'tmp' );
    I = ReadUI('it1'            ,'tmp',[0.5e9 1e9 1.5e9]);
    
    % using the auto-regressive model
    U = ReadUI('port_ut1' , 'tmp', 'AR', 'auto');



-----------------------
author: Thorsten Liebig

See also DFT_time2freq, AR_estimate