In the case of multiple of same matrix matA, like
matA.transpose()*matA,
You don't have to compute all result product, because the result matrix is symmetric(so only if the m>n), in my specific case is always symmetric! square.
So its enough the compute only for. ex. lower triangular part and rest only copy..... because the results of the multiple 2nd and 3rd row, resp.col, is the same like 3rd and 2nd.....And etc....
So my question is , exist way how to tell Eigen, to compute only lower part. and optionally save to only lower trinaguler part the product?
DATA = SparseMatrix<double>((SparseMatrix<double>(matA.transpose()) * matA).pruned()).toDense();
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