[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: arithmetic issues



 | From: Thomas Bushnell BSG <tb@xxxxxxxxxx>
 | Date: Sun, 23 Oct 2005 12:39:43 -0700
 | 
 | Aubrey Jaffer <agj@xxxxxxxxxxxx> writes:
 | 
 | > When different NaNs are returned depending on the circumstances
 | > creating them, I would like my implementation to display them
 | > like this:
 | >
 | >   #<not-a-number expt>
 | 
 | Sure, that seems fine.  We could mandate that as the readable written
 | representation!

It should *not* be a readable representation.  That serves only to
mask mathematical errors in saved datasets.  As Bakul Shah wrote:
"... IEEE754 says NaN is the result of an *invalid* operation, when an
operation's operands lie outside its domain."

And literal NaNs will find precious little use in programs if all
equality predicates return #f for them!