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| From: Sebastian Egner <sebastian.egner@xxxxxxxxxxx>
| Date: Tue, 14 Jun 2005 09:46:30 +0200
|
| Aubrey Jaffer wrote:
|
| > Function: limit proc x1 x2 k
| > Function: limit proc x1 x2
| >
| > ...
|
| The specification and implementation of LIMIT has really improved a
| lot. Good work! So LIMIT is now specified as a certain extrapolation
| algorithm using the points (x, f(x1 + x2/k)), k in {1..d}.
|
| Although I still have doubts that this functionality should go into
| the core of a general purpose programming language (for many programs
| it might not be relevant and it's also not essential for portability)
| this operation is certainly a reasonably well-defined numerical
| algorithm.
In the current version of SRFI-70 I removed the requirement for the
LIMIT procedure; changing it to a "library procedure". As LIMIT has
developed, it no longer has platform dependencies. It is most similar
to RATIONALIZE among Scheme procedures; so I moved its description to
follow RATIONALIZE in section 6.2.5.
Choices for its disposition are:
[a] LIMIT is a library procedure
[b] LIMIT is an optional procedure
[c] LIMIT is removed from SRFI-70
Choices for infinity notation are:
[d] 1/0, -1/0, 0/0
[e] 1/0., -1/0., 0/0.
[f] #i1/0, #i-1/0, #i0/0
Choices for (/ 0 0) are:
[g] (/ 0 0) is an error (implementations are not constrained)
[h] (/ 0 0) behavior is unspecified (must not signal error)
[i] (/ 0 0) returns 0/0 or signals an error
Choices for (expt 0 0) are:
[j] (expt 0 0) returns 1
[k] (expt 0 0) is an error (implementations are not constrained)
[l] (expt 0 0) behavior is unspecified (must not signal error)
[m] (expt 0 0) returns 0/0 or signals an error
What do you (all) recommend on these 4 issues?