The butterfly factorization function has been updated to allow using one or several permutations. This update makes the function fully match the reference paper  and is available for both pyfaust and matfaust.
In addition to the permutation functionality of the butterfly factorization, a new function named rand_butterfly has also been integrated in the wrappers (pyfaust, matfaust). This function allows to randomly generate a Faust according to butterfly supports. It brings a simple way to test the butterfly factorization using the full array of those random butterfly Fausts.
 Quoc-Tung Le, Léon Zheng, Elisa Riccietti, Rémi Gribonval. Fast learning of fast transforms, with guarantees. ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing, May 2022, Singapore, Singapore. (hal-03438881)