Nipals Functions
• Nipals(DATA, NumPC, maxiter, "scale/noscale", Acc)—Returns numPC principal components, calculated with a maximum of maxiter iterations from a matrix of multivariate DATA. The fourth argument may be set to "scale" if you wish to scale the data to the standard deviation, or "noscale" if you do not. The convergence accuracy is given by Acc, typically of the order of 10-10 or smaller.
• Nipals2(Nipals, numAddPC)—Returns the same output as the Nipals function, for numAddPC additional principal components.
The output of Nipals and Nipals2 contains the scores, loadings, cumulative variance explained, and the principal components in nested format. These can be accessed using matrix indexing or they can be extracted with the other built-in functions.
Arguments
• DATA is a matrix of multivariate data.
• NumPC is the number of principal components.
• maxiter is the maximum number of iterations.
• “scale” or “noscale” are arguments that specify if you wish to scale the data to the standard deviation or not.
• Acc is the convergence accuracy. It is typically of the order of 10-10 or smaller.
• Nipals is the nested matrix output of the Nipals or Nipals2 function.
• numAddPC is the number of principal components that are needed in addition to those already calculated by the nipals function.