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Functions for taking apart floating-point numbers
- To: Common-Lisp@su-ai
- Subject: Functions for taking apart floating-point numbers
- From: David A. Moon <Moon%SCRC-TENEX%MIT-MC@SU-DSN>
- Date: Sat, 04 Jun 1983 03:50:00 -0000
- In-reply-to: The message of 3 Jun 83 14:47-EDT from Robert A. Cassels <Cassels at SCRC-TENEX>
Date: Friday, 3 June 1983, 14:47-EDT
From: Robert A. Cassels <Cassels at SCRC-TENEX>
Proposal: Remove @f[float-exponent] and @f[float-integer-exponent], and
return those numbers as the second values from
@f[float-significand] and @f[float-integer-significand].
I think this was turned down last year, but I don't remember why. It sounds
reasonable to me, except that one would probably want to choose better names
for the two functions. I'm in favor of it.
Proposal: Add new functions @f[float-digits] and @f[float-precision].
I don't understand the need for both of these. It sounds like float-precision
is the only one you actually need; float-digits returns the same answer except
for certain exceptional numbers.
Proposal: Require the result of @f[float-integer-significand] to
reflect the precision of the floating-point number.
This sounds reasonable. The main competing proposal is that it return
a result "normalized to the right" by removing trailing zeros. Your
proposal seems slightly preferable to that.
Proposal: Clarify the result of @f[(float-sign 0.0)], @f[(float-sign
I think this is just a clarification, since the manual indicates that
float-sign with one argument never returns zero even if the argument is zero.