[scikit-learn] Which sparse matrix should be use for fit?

https://scikit-learn.org/stable/modules/svm.html Of the svm classes mentioned above, which sparse matrixes are appropriate to be used with them? https://docs.scipy.org/doc/scipy/reference/generated/scipy.sparse.csr_matrix... It is not very clear what matrix operations are used in fit(), so I can not tell what sparse matrixes should be used. Thanks. -- Regards, Peng