In the course of some recent experimentation I found it useful to have a built-in function to "flatten" an array of matrices to one big matrix, and I enabled such a function in my working copy of the gretl sources. The function in question takes as argument 1 an array of matrices and as argument 2 either "hcat" or "vcat": in the hcat case the member matrices are concatenated horizontally (which requires that they all have the same number of rows); under vcat they're concatenated vertically (requiring a common number of columns). In either case a hansl function could be written quite easily to do the job, but a built-in function is likely a good deal faster. Anyway, my particular need for this function has passed but I was wondering if others would find it useful. If so I can add it to git, if not I'll quietly retire it. Allin