nkshift

Shift data sequences

Syntax

Datas = nkshift(Data,nk)

Description

Data contains input-output data in the iddata format.

nk is a row vector with the same length as the number of input channels in Data.

Datas is an iddata object where the input channels in Data have been shifted according to nk. A positive value of nk(ku) means that input channel number ku is delayed nk(ku) samples.

nkshift supports both frequency- and time-domain data. For frequency-domain data it multiplies with e^inkωT to obtain the same effect as shifting in the time domain. For continuous-time frequency-domain data (Ts = 0), nk should be interpreted as the shift in seconds.

nkshift lives in symbiosis with the InputDelay property of linear identified models:

m1 = ssest(dat,4,'InputDelay',nk) 

is related to

m2 = ssest(nkshift(dat,nk),4);

such that m1 and m2 are the same models, but m1 stores the delay information and uses this information when computing the frequency response, for example. When using m2, the delay value must be accounted for separately when computing time and frequency responses.