Performance and Evaluation of Lisp Systems - Dreamsongs

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little else but function calls (fixnum arithmetic is performed as well), it is not
representative of the majority of Lisp programs. It is only a good test of function
call and recursion, in particular.
3.1.1 The Program
Here is the code for this program:
(defun tak (x y z)
(if (not (< y x))
z
(tak (tak (1- x) y z)
(tak (1- y) z x)
(tak (1- z) x y))))
We call this function as
(tak 18 12 6)
3.1.2 Analysis
When called on the above arguments, TAK makes 63,609 function calls and
performs 47,706 subtractions by 1. The result of the function is 7. The depth
of recursion is never greater than 18. No garbage collection takes place in the
MacLisp version of this function because small fixnums are used.
The following table is typical of the tables that will be used to report the
numbers of significant Lisp-level operations performed by the benchmark. The
previous paragraph and the following table convey the same information:
Meter for Tak
Item Count
Calls to TAK 63609
1−’s 47706
Total 111315
circulation. Because it was simple and because there were many results for it in the literature,
he felt that it would be a good initial test. Of course, John misremembered the function. But
we did not realize it until I had gathered a great many numbers for it. Alas, we are stuck with
this variant on Takeuchi.