Thanks much for the clarification - I hadn’t researched the Zygote pkg yet - but saw a comment to you about AD. I had planned on rerunning with mods to the methods today. You seem to be understanding many concepts rapidly - and are much more adept at Julia than myself. It seems a good choice for me coming from C++/Java - and seems to offer alternatives to satisfy my projects embedded CPU/GPU arch and concurrency requirements. Time will tell. I appreciate your help - BTW I purchased your book from Amazon today. Take care - Mike