Sorry, I had a typo. I meant UNsetting the macros for enabling external BLAS libraries. :-)
On Fri, Jul 9, 2021 at 1:20 AM 张瑞 <[email protected]> wrote: > dear Rasmus, > > thanks for your reply, I tried to add the code #define EIGEN_USE_BLAS, > but it still doesn't work. > > and I found actually multiplication was done, it failed to assignment to > the x matrix > > > if the code is like this , it can be compiled successfully: > > Matrix<double,8, 8> b; > > Matrix<double, 8, 1> l; > Matrix<double, 8, 1> x; > b.Zero(); > l.Zero(); > b*l; > > > -----原始邮件----- > *发件人:*"Rasmus Munk Larsen" <[email protected]> > *发送时间:*2021-07-09 04:57:30 (星期五) > *收件人:* [email protected] > *抄送:* > *主题:* Re: [eigen] dense matrix multiplication > > 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! >> >>
