It looks like your build of Eigen is set up to call the function gemv_ an external BLAS library for large matrices, possibly by setting the macro EIGEN_USE_BLAS. See the documentation here: https://eigen.tuxfamily.org/dox/TopicUsingBlasLapack.html
On Thu, Jul 8, 2021 at 2:57 AM 张瑞 <[email protected]> wrote: > dear all, > > > I'm a new user of Eigen, I want to get the multiplication of two matrix, and > met a confusing problem, and the code is as bellows(for simplicity, all > values are set to 0): > > > Matrix<double,8, 8> b; > Matrix<double, 8, 1> l; > Matrix<double, 8, 1> x; > b.Zero(); > l.Zero(); > x = b*l; > > > Compiled under the windows platform and vs2019 environment, there is a > fatal error LNK1120: > > " Unresolved external symbol _dgemv，funticon "public: static void __cdecl > Eigen::internal::general_matrix_vector_product_gemv<int,double,1,0,double,0>::run(int,int,double > const *,int,double const *,int,double *,int,double)" (?run@ > ?$general_matrix_vector_product_gemv@HN$00$0A@N$0A@@internal@Eigen > @@SAXHHPBNH0HPANHN@Z) " > > > But if I Reduce the matrix dimension, it works, like: > > Matrix<double,4, 4> b; > Matrix<double, 4 1> l; > Matrix<double, 4, 1> x; > b.Zero(); > l.Zero(); > x = b*l; > > very grateful for your help, thank you! > >
