If I understand correctly, the multi_array storage order determines which strides are larger than others. In short: if( order[I]>order[I+1]) then stride[I]>stride[I+1] However, the output from the attached code shows that this is not always true. In the attached code, the mono_tonic_print function tests the conditions and prints out the results. The following partial output: :count=3 :permut_v={ 1, 2, 0} :permut_i={ 2, 0, 1} :ma.ordering(*)==permut_v=1 :multi_array_strides:strides()={ 12, 1, 3} :monotonically increasing={ 0, 0} :is_mono_tonic=0 :expected_strides:{ 4, 8, 1} :monotonically increasing={ 1, 1} :is_mono_tonic=1 :count=4 :permut_v={ 2, 0, 1} :permut_i={ 1, 2, 0} :ma.ordering(*)==permut_v=1 :multi_array_strides:strides()={ 4, 8, 1} :monotonically increasing={ 0, 0} :is_mono_tonic=0 :expected_strides:{ 12, 1, 3} :monotonically increasing={ 1, 1} :is_mono_tonic=1 shows that the multi_array code fails this monotonic constrait when the order is one of: :permut_v={ 1, 2, 0} :permut_v={ 2, 0, 1} The code also shows a possible solution. This possible solution uses the inverse permutation instead of the original permutation to calculate the strides, as shown in the expected_strides function. There's also a macro, NO_INVERT_PERMUT, which, if defined, has expected_strides reproduce the multi_array strides, which may help narrow down the source of the error in multi_array's stride calculation. The output is also attached. If macro INDENT_OUTPUT is defined, the code requires: http://svn.boost.org/svn/boost/sandbox/variadic_templates/boost/iostreams/fi... http://svn.boost.org/svn/boost/sandbox/variadic_templates/boost/iostreams/ut... http://svn.boost.org/svn/boost/sandbox/variadic_templates/boost/utility/trac... http://svn.boost.org/svn/boost/sandbox/variadic_templates/boost/utility/inde... If you don't want to download those, then the output will not be nicely indented as shown in the attached output. HTH. -regards, Larry