The Package: PTAk Version: 1.1-4 performs

Principal Tensor Analysis on k modes

as the main multiway method of the package.

last released in R in CRAN contributed packages.

examples using PTAk


PTA-k modes is a multiway method to decompose a tensor (array) of any order, as a generalisation of SVD also supporting non-identity metrics and penalisations. 2-way SVD with these extensions is also available. The package includes also some other multiway methods: PCAn (Tucker-n) and PARAFAC/CANDECOMP with these extensions.

  • A comparison between a canonical SVD and a penalised SVD forcing components ($u and $v) to be smooth...


  • Now an example with fMRI data (brain x time x subjects) for a multi-subject verbal experiment without metrics or penalisations . The time series (for each voxel and each subject) were detrended, and each subject was scaled to variance one.


  • The same analysis using a non-identity metric for time -the inverse of a robust estimate of the within "group"-(without knowing the group structure) computed on the (brain x time) mean over subjects.
  • The same analysis using a identity metric but penalisation for time.

  • The same analysis using a identity metric but penalisation for time and space.

  • The same previous analysis using non-identity metric (the inverse of the within group as above) and penalisation for time and space.





  • One subject analysis using PCA, FCA FCA 4modes.

  • back to index
    Didier Leibovici
    Last modified: Thu Jul 5 10:21:34 BST 2006