I am using Dev-C++ with gcc 4.4.1 and boost 1.37.0 and MTL 4 (MTLVERSION 4\nMTLRELEASE beta-1\nMTLREVISION 6916 ) for matrix computation. And my code is the following : #define MATRIXCOLS 3 #define MATRIXROWS 3 #include <boost/numeric/mtl/mtl.hpp> using namespace mtl; using namespace mtl::matrix; typedef dense2D<double> Matrix; typedef dense_vector<double> Vec; ................................. using namespace mtl; using namespace mtl::matrix; const unsigned xd= 2, yd= 5, n= xd * yd; Matrix Kk(n,n),Hk(n,n),Rk(n,n);hessian_setup(Kk, 3.0);hessian_setup(Hk, 3.0); Rk=trans(Hk); Vec hxkk_1(n,0.0),zk(n,0.0),hxkk(n,0.0),hxkk_11(n,0.0); hxkk=zk-Hk*hxkk_1; hxkk= Kk*hxkk; //the * line ............................... and it is complied OK. But when it ran to the (*) line the result is : This application has requested the Runtime to terminate it in an unusual way, please contact the application's support team for more information. I found that the mailinglist in http://osl.iu.edu/research/mtl/mtl4/ is quite a place that almost no letters. When I use hxkk*=Kk; instead of the * line,even it can not be complied. So I write letter here for any experts to give me some advices. Can any one with kindness help me?