Nvalidate

Purpose

Validate the number PARAFAC or Tucker components.

Synopsis

result = nvalidate(x,ncomp,method,options);

nvalidate(result,x) %Plot earlier results

nvalidate(x,1:3,'parafac')  % Validate 1-3 component PARAFAC models

nvalidate(x,[1 1 1;3 3 3],'tucker') % validate [1 1 1] to [3 3 3] comp Tucker3 models

Inputs

• x multi-way array to be modeled
• ncomp number of components to be modeled. Set ncomp to [1:4] to test one -to four compenent models if using parafac. If using tucker, instead set ncomp to [2 2 2; 4 5 4] to check from 2 to 4/5 components depending on mode.

• method Either 'parafac' or 'tucker'

Outputs

The outputs of the nvalidate function are returned as a struct with the following fields

• ssq The sum-squared error. What to look for: look for sudden changes as in a Scree-Plot(often difficult) and look for sudden increase in number of local minima (replicate points for a number of components are not identical). This is often a good indication that noise is being modeled.

• models Cell of models where element {f,r} is the r'th model replicate fit with f components