dear list, I am using ublas from boost 1.32, gcc 3.3.3, solaris 9 I need to copy some independant submatrix (matrix_range) of a symmetric matrix. I use the assign() method to do so. first, I compile without NDEBUG, and a postcondition check in assignment is not met... Assertion failed in file /usr/local/boost/include/boost/numeric/ublas/matrix_assign.hpp at line 797: equals (m, cm) E: src/slamEkf.cpp:325: std::exception ** std::exception: ** external logic I checked that compiling with NDEBUG the assignement is not correct. If I copy the two submatrix using a stupid for loop, it works... I use the default version of symmetric_matric (lower), and I assign _upper_ part of the matrix. I tried to assign the _lower_ part of the matrix and it works ! nothing in the doc tells that using the assign() functions is different with symmetric_matrix... this problem arises only when assigning a submatrix to another submatrix. When assigning an expression to a submatrix in the _upper_ part of the lower symmetric matrix it works fine. Is it a bug ?? -- thomas