A problem with recursive calls

A problem with recursive calls is that they are expensive; a method invocation entails considerable overhead on the processor. It is, in general, better to avoid invoking methods if you want to improve performance to the last bit. On top of that, there is a limit to the depth of function calls that you can go to, before the program breaks. This is because a program has a stack to enable method invocation semantics, that actually gets a new element containing all variables and the position of the current instruction to the stack. This stack does not grow indefinitely, but instead is fixed in size; usually, it can hold a few thousand values, which means that if your method invocation is deeper than that, it will break and the program will exit with an error. This means that our insertion sort will break for an array containing more than a few thousand entries. On the other hand, it is generally easier to explain an algorithm in a functional form. To balance between...