On 11/28/22 9:59 PM, Taylor R Campbell wrote:

>> Date: Mon, Nov 28, 2022 at 8:38 AM
>> From: Bradley Lucier <xxxxxx@math.purdue.edu>
>>
>> This is obvious, I know, but perhaps all such statements could be changed to
>>
>>    Thus a nonzero r is negative iff d is negative.
>
> What I originally wrote is:
>
>    Thus when r is nonzero, it is negative iff d is negative.
>
> I guess this got garbled in translation from the original:
>
> https://mumble.net/~campbell/tmp/division.txt

This is nice language.  I recommend that the SRFI document say something
like this.

>> On another issue, can anyone point me to a list of simple unit tests for
>> all these functions?
>
> For MIT Scheme a long time ago I wrote a collection of randomized
> property tests (which, in retrospect, I implemented badly), but not a
> simple set of known-answer tests:
>
> https://git.savannah.gnu.org/cgit/mit-scheme.git/tree/tests/runtime/test-division.scm?id=631998ccfb7bc31bb94f00aff32d011560f95648
>
> Attached is a collection of known-answer test that you could try -- I
> generated it just now with MIT Scheme.  It tests the cartesian product
> of:
>
> - the five operators {floor/, ceiling/, truncate/, euclidean/, round/}
> - the nine numerators {0, 1, 2, 3, 4, 5, 6, 7, 8}
> - both signs for numerators
> - the eight denominators {1, 2, 3, 4, 5, 6, 7, 8}
> - both signs for denominators
>
> These 1440 test cases cover zero, units, primes, a square, a composite
> of distinct primes, and a cube.  (They don't, however, cover anything
> that requires bignum arithmetic.)  I haven't vetted these answers in
> any way other than verifying the tests pass in MIT Scheme -- I
> recommend running them through the property tests, and eyeballing them
> to spot-check for reasonableness.

Thanks, I'll use this idea.  (There's also the balanced/ family.)

Brad