getTrend - Data offset and trend information

Syntax

Description

T = getTrend(data) constructs a TrendInfo object to store offset, mean, or linear trend information for detrending or retrending data. You can assign specific offset and slope values to T.

T = getTrend(data,0) computes the means of input and output signals and stores them as InputOffset and OutputOffset properties of T, respectively.

T = getTrend(data,1) computes a best-fit straight line for both input and output signals and stores them as properties of T.

Examples

Compute input-output signal means, store them, and detrend the data:

% Load SISO data containing vectors u2 and y2
load dryer2
% Create data object with sampling time of 0.08 sec
data=iddata(y2,u2,0.08)
% Plot data on a time plot - it has a nonzero mean
plot(data)
% Compute the mean of the data
T = getTrend(data,0)
% Remove the mean from the data
data_d = detrend(data,T)
% Plot detrended data on the same plot
hold on
plot(data_d)

Remove a specific offset from input and output data signals:

% Load SISO data containing vectors u2 and y2
load dryer2
% Create data object with sampling time of 0.08 sec
data=iddata(y2,u2,0.08)
plot(data)
% Create a TrendInfo object for storing offsets and trends
T = getTrend(data)
% Assign offset values to the TrendInfo object
T.InputOffset=5;
T.OutputOffset=5;
% Subtract specific offset from the data
data_d = detrend(data,T)
% Plot detrended data on the same plot
hold on
plot(data_d)

See Also

detrend | retrend | TrendInfo

How To

• Handling Offsets and Trends in Data

Free Control Systems Interactive Kit

Learn more about resources for designing, testing, and implementing control systems.

Get free kit

Trials Available

Try the latest control systems products.

Get trial software