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Re: inexactness vs. exactness

This page is part of the web mail archives of SRFI 70 from before July 7th, 2015. The new archives for SRFI 70 contain all messages, not just those from before July 7th, 2015.

William D Clinger <will@xxxxxxxxxxx> writes:

> (Under the unfortunate influence of a flawed paper that was
> presented at the 2004 Scheme Workshop, several Scheme programmers
> have been incanting that it is not Scheme's inexact numbers that
> are inexact, but certain arithmetic operations that are inexact.
> There is a grain of truth in that slogan, but it seems to have led
> some people to an incorrect conclusion: that they can identify the
> inexact operations.  

While I don't think we need to get into an argument about the flaws of
the paper, the above paragraph could be read to imply that the paper
draws that incorrect conclusion.  Just for the record: that ain't so.

> With R5RS arithmetic, *which* operations are inexact is determined
> by the implementation, not by the R5RS or by the programmers.  The
> computable reals are an important example of this fact.)

... and the paper tries to argue (arguably in a flawed manner---or
not) that this causes problems, which is why we proposed to change
exactly that aspect of the R5RS generic arithmetic.  This thread is no
proof, but certainly an indication that there is a certain amount of
confusion over the nature of exactness in R5RS.

Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla