Find time offset that best lines up two position curves using appdesigner

% I have time histories of position (time, X, Y) from two different sources (KTM and RNET). Both sources have the target goin over about the same path, but % % there appears to be a time offset. I want to find the time offset to that best lines up the data for comparison.

properties (Access = private)

RNETTable

KTMTable

end

methods (Access = public)

% time histories from two sources

% are stored in tables

% SSDelta applies a time shift (dTime) to one time history of position

% (time, X, Y) and computes the sum of the square of the

% differences of the X and Y components

function SSD = SSDelta(app,dTime)

% apply time shift to one source

RSOD=app.RNETTable{:,'SOD'}+dTime;

% interpolate the X and Y data from RNET to times of the KTM

% since they are not synchronized and compute the sum of the

% squares of the differences

DX=interp1(RSOD(:),app.RNETTable{:,'Xnb'},app.KTMTable{:,'SOD'})-app.KTMTable{:,'x_m_'};

DX=DX.*DX;

DY=interp1(RSOD,app.RNETTable{:,'Ynb'},app.KTMTable{:,'SOD'})-app.KTMTable{:,'y_m_'};

DY=DY.^2;

%return the sum of the squares of the differences

SSD=sum(DX)+sum(DY);

end

end

% From a push button function callback, I use fminbnd to determine the time offset that results in the

% minimum sum of the squares of the differences

dTime=fminbnd(@SSDelta,-20.0,20.0);

% I get the error

Undefined function 'SSDelta' for input arguments of type 'double'.

Error in fminbnd (line 238)

fx = funfcn(x,varargin{:});

% I am open to an alternate approach, although I have a number of these, so I would like to use appdesigner

Answer 1

[Umar]

Hi Stephen,

It appears that the function `SSDelta` is not recognized within the context of the `fminbnd` optimization call. This issue arises because the `SSDelta` function is defined as a method within the class or app that you are working with (assuming it is an App Designer app given your reference to `appdesigner`).

To address this problem, you need to ensure that the `SSDelta` function is accessible within the scope of the optimization call. One way to achieve this is by explicitly referencing the method within your App Designer app.

You can modify your code as follows:

1. Ensure that the `SSDelta` method is defined within your App Designer class or app script. 2. Modify the optimization call to directly reference the method within the app instance. You can do this by calling `app.SSDelta` instead of just `SSDelta`.

Here's an updated snippet of your code with these modifications:

 % Inside your App Designer class or script 

methods (Access = public)

function SSD = SSDelta(app,dTime)

 % Your existing SSDelta function implementation 
end 
end  

% Update the optimization call to use 'app.SSDelta'

dTime = fminbnd(@(x) app.SSDelta(x), -20.0, 20.0);

By making these adjustments, you should be able to resolve the "Undefined function 'SSDelta' for input arguments of type 'double'" error and successfully run your optimization routine to determine the time offset that minimizes the sum of squares of differences between your data sources.

Hope this will help resolve your issue.

[Stephen Marsden]

That worked. Thanks!