A function to calculate sufficient statistics and out cross-product matrix efficiently for medals

This function allows you to calculate the sufficient statistics to center and scale each column in the huge (long) matrix X for medals, then outputs the center and scaled cross product matrices. This should be the first step of the MEDALS pipeline

moment.cor.mat(path.img.list, path.mask.list, mpower = 4,
  verbose = TRUE)

Arguments

path.img.list	A list of sublists, where each sublist is a list of paths to the files for each imaging modality (ex. T1w, T2w, DWI, etc.) for a particular subject. This has to contain at least one sublist
path.mask.list	A list of paths to the brain mask for each subject. This should be in the same order as the sublists for path.img.list
mpower	A scalar specifying the highest moment wanted for the MEDALS analysis. (Should be at least 1)
verbose	print diagnostic messages