Flexible Floating-Point Standard Proposal (was: Decimal ... JOSS)

Flexible Floating-Point Standard Proposal (was: Decimal ... JOSS)

Post by jsavar » Fri, 18 Mar 2005 01:23:23

Looking at your web page further, I see that what you appear to be
proposing is a standard for the following:

A software floating-point support package for a computer that will
receive a request that it provide floating-point computations which
satisfy certain properties, and which will meet that request using a
floating-point format supported by the underlying hardware if
possible, and will simulate a format in software with those properties
if necessary.

A hardware floating-point coprocessor could also implement this as a

This is an interesting idea. Why is the committee dealing with IEEE
754 ignoring it?

There is actually a simple reason. Although an interesting idea, it
would require effort to implement. Thus, the fact that it exists as an
alternative is not enough to lead to an effort to standardize it.

The effort to create IEEE 754 resulted from a groundswell of demand
among people using computers to perform numerical calculations, based
on the fact that the floating-point offered on at least some
architectures (i.e., the hexadecimal floating-point of the IBM 360
series) was inadequate, and that gradual underflow was sorely needed.

Some items, such as affine infinity, were dropped from IEEE 754 - they
were implemented on the 8087, but not on its successors, therefore.

If enough people who work with numbers think that something like your
proposal is needed, then, once they take it up, this idea *will* go
somewhere; but there has to be a real demand before it is felt that it
is worth the effort.

John Savard

Flexible Floating-Point Standard Proposal (was: Decimal ... JOSS)

Post by David W. C » Fri, 18 Mar 2005 07:52:53


I think you meant to say that the projective infinity was dropped. The
affine infinities were retained in IEEE 754.