Thank you for your teaching me a lot.
Without your very kind instruction, I couldn't understand what maple showed as the result of quicksort.
That program is on Advanced Programming Guide of Maple 9, page 10. And, I asked about it, as I thought it is important to know about how maple invocates a program with nested procedures. In the Introductory Programming Guide,
I thought that there was no description of layers of invocated level, which I expressed as this as I can't see how I should express this. At least, there was no explicit explanation about it in it. Seeing "top level" in the book, I couldn't understand it because I didn't know layers.
And, thank you for telling me about "infolevel." This is surely very helpful tool. I will absolutely use it from now.
And, thank you for showing me a model of indentation of a code. Identation is explained in introductory programming gude, p225, and the original code of quicksort had an indentation. But, watching your indentation of the code will be definitly helpful to me as a model in writing a code.
First, I thought I would delete this first post of my question about quicksort, to find no reply from others for a while , and actually deleted this question. But, then, I noticed your above reply to this question, after I read your reply to another related question of me about nested procedure of quicksort. The present question was not actually deleted very luckily to me.
Thank you very much for a lot of your instruction to me.