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Re: numeric tests
From: |
Marius Vollmer |
Subject: |
Re: numeric tests |
Date: |
28 Jul 2001 15:04:48 +0200 |
User-agent: |
Gnus/5.09 (Gnus v5.9.0) Emacs/21.0.102 |
Dirk Herrmann <address@hidden> writes:
> .I have re-implemented the string->number functionality to
> (hopefully) closely match the syntax as it is specified by R5RS.
> The new implementation tries to be as accurate as possible, i. e. a
> rational number a/b is first read as two exact integers, and
> afterwards one single division is performed.
I like this!
> Just some more remarks: The new implementation in its current state is
> much slower than the old one.
In all cases, or only in the cases where it has better behavior than
the previous code?
> I have at first aimed at correctness and did not put a lot of effort
> into performance. Should I commit it to the CVS trunk anyway?
Yep, I'd say so.
> However, "#e9/10" _is_ accepted and gives 1, similarly "#e1.2" is
> accepted as well and also gives 1
I don't think they should be accepted. If the user explcitely
requests an exact number and we can't give it to him, we should not
stealthily return an inexact number, or a number that is exact, but
not the one the user has requested.
> I was not quite sure about the last two examples "#e9/10" and "#e1.2".
> R5RS does not state that the #e prefix in conjunction with an inexact
> number should be disallowed.
Hmm, I don't understand. What do you mean with "in conjunction with
an inexact number"? "1.2" is not inexact by itself, it is exactly
12/10.