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- The previous version of the * operator for matrix was too clever. It was giving a lazy object and then rewriting C = A *B into gemm (a,A,B,0,C). The pb was in case of aliasing : when e.g. C = A, or is a part of A. gemm is not correct that case, and as a result generic code like a = a *b may not be correct in matrix case, which is unacceptable. - So we revert to a simple * operator for matrix that does immediate computation. Same thing for matrix* vector - we also suppress a_x_ty class. -> for M = a * b, when M is a matrix, there is no overhead due to move assignment -> however, when M is a view, there is an additionnal copy. -Correctness comes first, hence the fix. However, if one wants more speed and one can guarantee that there is no aliasing possible, then one has to write a direct gemm call. -> det_manip class was adapted, since in that case, we can show there no alias, and we want the speed gain, so the * ops where replaced by direct blas call (using the array blas interface). -> also gemm, gemv, ger were overloaded in the case the return matrix/vector (i.e. last parameter of the function) is not an lvalue, but a temporary view created on the fly.
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