Path: utzoo!attcan!uunet!mcsun!sunic!ifi!m2cs.uu.no!tomas
From: tomas@m2cs.uu.no (Tomas Felner)
Newsgroups: comp.windows.news
Subject: Re: Integers, mod, and some wallpaper patches
Message-ID: <1989Nov6.075307.10547@m2cs.uu.no>
Date: 6 Nov 89 07:53:07 GMT
References: <28574@sparkyfs.istc.sri.com>
Organization: Modula-2 CASE Systems A/S, Oslo, Norway
Lines: 38

zwicky@sparkyfs.itstd.sri.com (Elizabeth Zwicky) writes:

>In particular, div and exp are both documented in the Red Book as
>always returning reals. In NeWS, when div returns an integer, it is
>type integer. This makes sense, given that the NeWS manual says that
>any real small enough to be an integer (i.e., that will fit in 16 bits
>of integer and 16 bits of fraction), will be an integer, which will
>magically look like a real to type. So div should be returning a real,
>which is small enough to be converted into an integer, which then gets
>turned back into a real if it has a fractional part. Confusing, but
>fine. That is, until you get to exp, which really truly does always
>return a real; "2 2 exp dup = type =" will give you "4 realtype". What
>a nusiance.

>Next, we have mod and idiv, both of which are documented in the red
>book as requiring integer arguments. mod does in fact require
>arguments of type integer, and will return a typecheck if run on 2.4,
>2 2 exp, or any number over 32767. idiv neither requires integer
>arguments, *nor is guaranteed to return them*; try "2 17 exp 2 idiv
>type =". I assume this is due to the magic conversion of integers to
>reals once they get to big; on the other hand, since mod will return a
>typecheck, it is not helpful. Then again, cvi does no better; try
>"32768 cvi type =". Just what I wanted; a real result from converting
>to an integer. And once again, mod will blow up.

I once had a similar problem. Depending on how many zeros you have after
the comma you get either a realtype or an integertype. Try the following:
"1.0000 dup == type ==", you will get an integertype! If you type:
"1.00000 dup == type ==" you will get a realtype!!! Now, which one is
correct ??

Tomas
-- 
                          Tomas Felner
     Modula-2 CASE Systems AS  |  Internet: tomas@m2cs.uu.no
            Maridalsveien 139  |  Phone: +47 2 379784
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