It's not that simple. If you allocate a matrix, for example, you don't just need enough RAM to do it, you need a large enough single contiguous block of RAM. That's a .NET requirement, not something imposed by PTC. I compared the 32 bit Matlab and Mathcad, and the maximum matrix size was about the same, and far short of the total available memory. The best you can do is close other applications, and allocate any large matrices at the top of the worksheet, before the available memory gets chopped up by anything else. You should also be aware that if you assign a value to a variable, say M, and then further down the worksheet assign a new value to that variable, M, they are not actually the same variable. You have two different M's, both using memory. You can minimize the memory drain caused by this by putting intermediate calculations that generate large matrices in a program. When the program exits the memory is freed. The memory used by variables at the worksheet level is only freed when the worksheet is closed. Richard
