Hi, I was just wondering if there is a bug in ublas (boost version 1.47): when I use the following code (in debug mode): ublas::matrix<double> m; ublas::matrix<double> m2; m2 = m; this compiles in MSVC 10, but produces a runtime error "Expression: invalid null pointer". I had a look at some of the underlying ublas code, and found that default initialisation of matrices makes the underlying data pointer "data_" be set to NULL, and that when one matrix is copied to another, std::copy is invoked to copy one data_ to the other. However, I looked at the MSVC std::copy definition, and it seems to check for NULLness of the pointers. The following link explains this in more detail: https://connect.microsoft.com/VisualStudio/feedback/details/558044/std-copy-... On the plus side, I have no such problem when running the above code in linux. Thanks, Peter