Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!jato!vsnyder
From: vsnyder@jato.jpl.nasa.gov (Van Snyder)
Newsgroups: comp.lang.fortran
Subject: Re: Cheating on the types
Message-ID: <1991Mar29.014537.23918@jato.jpl.nasa.gov>
Date: 29 Mar 91 01:45:37 GMT
References: <1991Mar20.195732.15376@appmag.com> <4554@alliant.Alliant.COM> <1991Mar25.163447.10166@cl.cam.ac.uk>
Reply-To: vsnyder@jato.Jpl.Nasa.Gov (Van Snyder)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 42

In article <1991Mar25.163447.10166@cl.cam.ac.uk> cet1@cl.cam.ac.uk (C.E. Thompson) writes:
>In article <4554@alliant.Alliant.COM> tj@Alliant.COM (Tom Jaskiewicz) writes:
>>In article <1991Mar20.195732.15376@appmag.com> pa@appmag.com (Pierre Asselin) writes:
>>}This simplified fragment violates the standard by passing reals to a
>>}routine that expects integers.
>>}
>>}      program wrong
>>}      real rin, rout
>>}      rin= 0.577215665          ! or whatever...
>>}      call icopy(rin, rout)
>>}      write(6,*) rout
>>}      end
>>}
>>}      subroutine icopy(iin, iout)
>>}      integer iin, iout
>>}      iout= iin
>>}      return
>>}      end
>>}
>>}Seems fairly innocuous, though.  Q:  are there implementations
>>}where it would fail ?
>>
>>Yes.  It been 10 years since I've used one, but there is at least one
>>Fortran implementation that uses 16 bit INTEGER's and 32 bit REAL's.
>>(this in itself violates Fortran-77).
>>
>
>From the mists of time: on TITAN (and other Atlas-1 and Atlas-2 Fortran
>implementations as well, I expect) integers were halfwords (24 bits) while
>reals were words (48 bits). The above code would not have worked... [stuff 
> deleted]

Also from the mists of time:  I think on CDC 6600/7600, an integer was
represented using only the fraction of a floating point number, with the
exponent zero.  If a number with zero exponent was acted upon by a floating
point instruction, or a number with non-zero exponent was acted upon by an
integer instruction, interrupts happened.  But I may have this wrong.

-- 
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