now I need to think of what it means in the program.

You can't pass arrays to a sub. The only thing that can be passed to a sub is a list of scalars. The solution is to pass references to arrays, references being scalars.

In thinking about this I believe what is happening is like "nesting".

I didn't look at how recursion is used here, but it's usually used to divide and conquer. Let's take merge sort, for example.

Sorting 

+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

[download]
is done by sorting 
+---+---+---+---+---+---+---+---+-------------------------------+
|   |   |   |   |   |   |   |   |                               |
+---+---+---+---+---+---+---+---+-------------------------------+

[download]
and 
+-------------------------------+---+---+---+---+---+---+---+---+
|                               |   |   |   |   |   |   |   |   |
+-------------------------------+---+---+---+---+---+---+---+---+

[download]

independently then merging the results. How does it sort the two halves? Well by breaking each down into two halves and sorting those. Etc.

In reply to Re^3: Total Syntax Confusion Plus by ikegami
in thread Total Syntax Confusion Plus by RobertJ

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